Chapter VI:
CHAPTER VI: ON THE UNITY OF THE DIVINE ESSENCE
§ 95. From the definition of God, it is obvious that we must consider in God (1) the unity of His essence and (2) the divine attributes, which are either essential or relative.
(I) It is evident on the basis both of the statements of Scripture and of the weight of rational arguments that God is one. When we say that God is a spiritual essence (from Exod. 3:14) or a spirit (from John 4:[24]), then the words “essence” or “spirit” are not some universal idea abstracted by the mind from individual things that befit God and angels equally. Rather, they signify an infinite thing [res], one in number, actually existing, utterly simple, common equally to the three persons of the Godhead. It is predicated neither univocally nor analogically about God and angels or other creatures, but [it] is predicated in a fully unique manner, because an infinite and finite essence, the uncreated Spirit and a created spirit, are categorically different [plusquam toto genere differant].
On the basis of this principle, we deduce the unity of God or of the divine essence, which Scripture proves with three classes of arguments: (1) by simple affirmation, when it asserts that God is only one; (2) by simple negation, when it denies that there are multiple gods; (3) by exclusive declaration, when it declares that besides the one true God there is no god before or after Him. (See our treatise On the Nature of God in our Commonplaces [1610 Loci Theologici, locus 3], § 40.) Deut. 6:4 stands forth as the classic passage: “Hear, O Israel, the Lord your God is one God,” and Christ quotes this in Mark 12:[29]. The Jews not only read these words every day but even inscribe them on clear parchment that they tie between the hair and forehead and on the left arm. They do not change anything of the entire Law so as to regard it as worthy of some religious honor, according to P. Fagius on Exodus 13. The explanation of unity is that it speaks of a thing not divided in itself but divided from any other thing. The rational arguments in favor of supporting the unity of the divine essence we draw (1) from simplicity, (2) from infinity, (3) from perfection, (4) from supreme goodness, (5) from the authority of dominion. (See the Damascene, Orth. fid., bk. 1, c. 5.)
§ 96. (II) As God is the greatest being [summum ens], so also He is maximally one. Tertullian, Adv. Hermog., c. 17: “The status of the one God vindicates this rule: He is one only because He is the only God. He is the only God only because there is nothing with Him.” Blessed Luther says in his commentary on Genesis 1 that God is one “in the highest unity” and, so to speak, “in the utterly one unity [unissima unitate].”
Metaphysicians argue that something is said to be one either of itself or by accident. God is not called “one” by accident because this is an incomplete kind of unity. Something is one of itself either perfectly or imperfectly—imperfectly (1) according to continuity, (2) according to subject, (3) according to genus, (4) according to species, (5) according to definition. Because these types of unity are imperfect, they also are inadequate for God, who is called one neither according to subject nor genus nor species. Rather, He is called one in the most perfect mode of unity, namely, as an utterly simple and undivided essence. Thus when it is claimed that God is one in number and maximally one, His unity is being considered not as the beginning of a number and reductive into the category of quantity, but as it is convertible with being and is transcendental, signifying nothing else but an undivided being.
** “One” is attributed to God (1) affirmatively, (2) exclusively. In the former way we affirm “one” not only about God but also about any other thing under God that is one or some one thing. In fact, in this sense “one” does not deny or remove other similar things of the same nature, genus, or species but merely denies a division and thus a multiplicity in the actual thing that is said to be “one” and sets up a distinction or division from other things. In this way it is self-evident that God is one. In the latter way, unity is proper to God alone. For “one” excludes the company of other similar things in the same way as the sun is said to be “one” because there are no other suns. **
Bernard, De consid., bk. 5, col. 1048:
There is a unity that can be called collective, as when many stones make up one pile of stones. There is also a constitutive unity, as when many limbs constitute one body or many parts one whole. There is also a conjugative unity by which it happens that they are no longer two but one flesh. There is a native unity by which soul and flesh are born as one man. There is a unity of power by which a man of virtue strives to be found not of unstable or dissimilar power, but to be found always one with himself. There is a harmonious unity, as when many people have one heart through love. There is a votive unity, as when a soul clings to God with all its vows and is one spirit. There is a unity of honor, as when the Word of God assumes our dust into one person. However, to the extent that all of these are related to that great and, so to speak, “unique one” where consubstantiality makes unity, if you assimilate any one of them to this “one,” it will be one in some way; but if you compare them, in no way will it be one.
Therefore as God is supreme being, He is maximally one: (1) because He is being, which is convertible with “one”; (2) because He is a singular being, which is maximally one; (3) because He is an utterly simple being, separated far from the multitude of diverse things. Because our mind cannot conceive of a greater or more intimate unity than a unity of essence and number, therefore we say that God is one in essence and in number.
But what should we respond to those words of Basil: “We do not confess that God is one in number but that He is one in nature” (Epistle 141), and of Rufinus: “God is not one in number but in universality” (Expos. symb., sect. 6)? We respond. He is said to be one in number: (1) Absolutely. He is one in such a way that He alone exists and besides Him there is none other of the same essence. (2) Relatively. He is one in such a way that in addition to Him there are others of the same essence. Or unity is either (1) arithmetic or quantitative, (2) or it is essential or transcendental. In the case of God we deny numerical unity in a relative or quantitative sense but not in an absolute and transcendental sense. That is why Victorinus says that “God is one in three persons more than in number” (Contra Arian., bk. 3), because even in those things that are called one in number, some multiplicity can always be discovered, but this is not permitted in the case of the divine essence.
The use of the doctrine of the unity of God.
§ 97. The use of the doctrine of unity is either theoretical or practical. The theoretical use consists of refuting arguments against all who deny the unity of God, either directly or obliquely. Directly: (I) Outside the Church the heathen deny the unity of God when they introduce a multitudinous army of gods, as the Damascene says (Orth. fid., bk. 1, c. 10). Rom. 1:23: “They have exchanged the glory of the incorruptible God for images resembling corruptible man or birds or animals or reptiles.” Gal. 4:8: “You used to be in bondage to those that by nature are not gods.” Augustine carefully discusses this polytheism and idolatry of the heathen in the first books of De civ. Dei. “Who can number the gods of the Romans, native and imported, of heaven, of earth, of hell, of seas, of fountains, of rivers, and, as Varro says, certain and uncertain, in all kinds of gods as in souls, males and females?” (De civ. Dei, bk. 3, c. 12). De civ. Dei., bk. 4, c. 8: “How can we mention in one passage of this book all the names of the gods and goddesses that they themselves could barely include in great volumes as they distributed the proper duties of the deities to individual matters?” Here he lists various names of the gods, and in c. 16 he calls them “a crowd not of gods but of demons,” and in c. 23, “not the power of those whom one should worship but the sins of those who worship them.” According to the same Augustine, Scaevola made three kinds of gods: “gods of poets, of philosophers, of princes.” Lucian divides them into “heavenly, marine, and underworldly,” and Porphyrius divides them into “heavenly, ethereal, aerial, aquous, terrestrial, and infernal.” Some teach that there were three ranks of gods among the heathen. (1) The first would include the heavenly gods, twelve of which were called the primary and select gods. Ennius includes them in this couplet:
Juno, Vesta, Minerva, Ceres, Diana, Venus, Mars,
Mercury, Jupiter and Neptune, Vulcan, Apollo.
(2) The second contained those in the middle, that is, heroic and outstanding men whose souls they thought lived partly in the air, partly on earth. (3) The third included Pluto with his guard from Tartarus. Themistius is said to have set forth three hundred ideas of the philosophers about God in his oration Ad Valentem. (See Socrates, Hist. eccles., bk. 4, c. 27.) Against this insane madness of the heathen we correctly set forth the statement of Epiphanius: “Polytheism is worse than atheism.”
(II) There are those in the Church who have undermined the unity of God. (a) In the second century after Christ’s birth, Valentinus attributed individual works of God to individual gods. (See Tertullian, Adv. Valent.; Irenaeus, bk. 1, c. 1; Epiphanius, Haeres., 31; Theodoret, Haeret. fab., bk. 1, c. 10; etc.)
(b) In the same century Marcion, the disciple of Cerdo, introduced two gods: one who was righteous and punished sin severely, whom the Old Testament called “God” and “the Lawgiver”; the other who was patient and kind, whom the New Testament called “God” and “the author of the Gospel.” (See Irenaeus and Augustine.) Philastrius reports his heresy a little differently. He introduced two principles: one good and one evil. Epiphanius said that he established three principles: one invisible, the second visible and a worker, the third midway between the invisible and the visible, namely, the devil. (See Tertullian, Contra Marc., bk. 1, p. 150; Irenaeus, bk. 1, c. 29; Epiphanius, Haeres., 42, p. 137; Theodoret, Haer. fab., bk. 1, c. 28; etc. See also the Cent. Magdeb. 2., c. 5.)
(c) In the second century, Manes (after whom the Manichaeans are named) invented two gods who are ungenerated and eternal and opposite to each other: one good and the cause of all good in nature, the other evil, from whom come the evils of both fault and punishment. Others report that these were God and matter and that he called God “light” and called matter or material “darkness.” (See Epiphanius, Haeres., 66, p. 281; Theodoret, Haer. fab., bk. 1, last chapter; Leo, Serm. 4. quadrag.; and Augustine, De haeres., vol. 6, c. 46.)
(d) The Tritheists introduced three gods. Nicephorus (Hist., bk. 18, c. 47) and Suidas (col. 410) report about Johann Philoponus, called “The Grammarian,” that he claimed that “three divine persons are the true God in the way that three men are one man. Therefore as we place three substances in three men, so also he claimed the same thing in God.” Theodoret mentions the same thing about the heretical Peratae (Haer. fab., bk. 1, c. 19). Cyril attributes the same error to Porphyrius in Contra Julian., bk. 1, where he says: “He thought the same thing as Arius, namely, that there are three gods in the Trinity.” You see, because the Arians say, “The Son is less than the Father and the Holy Spirit less than the Father and the Son,” they also had to assert different substances in the Trinity. For this reason the Arians were also called Porphyrians. (See Constantine in Socrates, bk. 1, c. 6; Theodosius, C. de haer., last book; and Augustine, De agone Christi, c. 15.) Augustine also mentioned some people who said, “God is one in essence in the same way as many men are said to be one with respect to essence.” The three persons, however, are the one true God not only in essence but also in number, not three gods divided among themselves. In the previous century, Valentinus Gentilis claimed that there were three spirits differing in eternal, essential number (Proth., 20 and 23).
(2) Those who give to creatures the honor owed to God destroy the unity of God indirectly. (See our commonplace [1610 Loci Theologici, locus 3 (On the Nature of God)], § 46.)
Whether the unity of the divine essence removes the Trinity of persons.
§ 98. Vindication of abuse also pertains to this theoretical use. For from the unity of the divine essence the Photinians draw their argument against the Trinity of persons, as is evident from the Catech. Racov., p. 57, and from all the writings of the Photinians published against the mystery of the Trinity. In their writings this argument is always placed first: “The divine essence is one; therefore there are not three distinct persons in it.”
We respond. (1) Christian simplicity responds that both are written in the Word: that the true God is one and that the Father, Son, and Holy Spirit are one, that is, that the three distinct persons are one. Therefore we should embrace both in faith and hold our reason captive to faith in this mystery.
(2) We have shown in its own commonplace that the rule of faith we are to accept is complete and that parts of it should not be opposed to each other. The rule of faith teaches that God is one. The same rule of faith teaches that the Father is God, that the Son is God, and that the Holy Spirit is God. Therefore we must not oppose these different parts in the rule of faith to each other nor should we oppose the one to the other out of the perverse judgment of reason.
(3) Just as the Tritheists sin, who attack the unity of the essence of God on the basis of those passages of Scripture that testify that the Father is God, that the Son is God, and that the Holy Spirit is God, so also the Photinians sin in the same manner when they attack the Trinity of persons in the Divinity on the basis of those passages of Scripture that testify that the true God is one. It is a common source of error to pass judgment on the things set forth in the rule of faith on the basis of a precept of human reason. Because reason claims that these are contrary and opposed to each other, they think they must depart from the literal meaning of the words in the one in order to establish the other. A similar example of error occurs in the fact that as the Manichaeans once used to assail the truth of the human nature on the basis of passages that place the divine nature in Christ, so the Photinians attack the divine nature on the basis of passages that teach we must acknowledge a human nature in Christ. Vigilius writes against them beautifully, Contra Eutych., bk. 2, p. 34:
When a Manichaean looks at such great miracles of power that the Son of God has performed, he is unwilling to confess that Christ is a man. When a Photinian notes the nature of our body in Him, he judges that Christ is not God. The former does this to propagate Christ’s powers, the latter to reinforce His weaknesses. The former alleges these powers as heralds of Christ’s deity, the latter alleges those weaknesses as heralds of His humanity. The majesty of such a great name calls the former away from a profession of Christ’s humanity, while the humility of the injustices that he sees as unworthy of God calls the latter to a confession of Christ only as a man. The miracles distract the one; the sufferings slow the other. The former is deceived by the deity; the latter is offended by the humanity. The former says, “He is God”; the latter, “He is man.” It is a great miracle that the truth is confirmed by attacking Him, and both speak the truth while each is lying. Listen, then, O Manichaean: You speak the truth that He is God, but you are deceived in saying that He is not also man. Listen, then, O Photinian: He is truly man, as you say, though not in the way you say, but He is also God, which you wickedly reject. He is God as much as a Manichaean denies that He is a man, and He is man as much as you do not believe that He is God.
We respond in precisely the same way when the Photinians oppose the unity of essence to the plurality of persons in God.
(4) Therefore, for all the objections of the Photinians that they declare in this argument, one distinction is sufficient—the distinction between the infinite, creating essence and the finite, created essence. Concerning the finite, created essence, it is quite true that the same thing, one in number, cannot simultaneously be complete in many persons, just as it is quite true that any finite, created person has his own peculiar essence. But concerning the uncreated, utterly simple, infinite, and all-creating divine essence, we say most truthfully that because of its supreme simplicity and infinity, it can be in multiple distinct persons without any multiplication or division of itself.
(5) Consequently, when they press, saying, “The essence of God is one not in species but in number and, therefore, cannot be common to several persons—or if it does become common to several, it is no longer one in number,” then we respond in this way: In the case of created things and multiplied and individual persons, essences are multiplied in number because no created essence is its own being nor is any created essence infinite. The divine essence, however, is its own being and is infinite; therefore because of its supreme simplicity, perfection, and infinity it can be in multiple persons.
Ambrose writes: “In some way the Church takes the middle road between Gentiles and Jews. Gentiles multiply and divide the divine nature as they put one nature in Saturn and another in Jupiter. The Jews, on the other hand, not only make one divine nature but also one person. The Church, however, confesses multiple persons, contrary to the Jews, and only one divine nature in these persons, contrary to the Gentiles” (De fide, bk. 1, c. 5). Bernard states it beautifully, De consid. ad Eugen., bk. 5:
Do we destroy what is said about unity when we bring in the Trinity? No, rather, we establish the unity. We say the Father, we say the Son, we say the Holy Spirit are not three gods but one. What does that number without number—so to speak—want for itself? If three, how is that not a number? If one, where is the number? … We may say it is three but not to the prejudice of unity. We may say one but not to the confusion of the Trinity. After all, names are not empty things nor are they hollow words without meaning. This is Sabellian. Who asks how what we say is catholic can exist? Let it be enough for him to hold that this is so. It is not clear to reason, yet it is not uncertain to opinion but it is persuasive to faith. This mystery is great and indeed worthy of our honor, but we should not investigate how plurality is in unity—and in this unity—nor how unity is in plurality. To investigate this is rashness, to believe it is piety, to know it is life and even eternal life.
And later: “When I say ‘one,’ the number of the Trinity does not disturb me, for it does not multiply nor change nor divide its essence. Again, when I say ‘three,’ the consideration of unity does not reprove me, for it neither forces those and any three, or those three, into confusion nor reduces them to singularity.” For the sake of some illustration, they offer “faculties of the soul,” which are different from each other yet really are one with the soul, but human curiosity always finds something to answer.
(6) If they say, “Hypostasis (person) is nothing else but a single nature and substance; therefore because there is one nature in God, there will also be one person,” we respond: The Scholastics respond by denying the major premise because the hypostasis adds an incommunicable substance to the intellectual nature and substance. But because hypostases are not multiplied in created things unless their natures are also multiplied, their argument (they say) depends on the proposition: “Because hypostasis in humans is something absolute, but in divine persons the hypostatic property is a relationship, therefore hypostatic properties and hypostases can be multiplied without multiplying nature or essence, which is something absolute.” They say, then, that no contradiction is involved when plural subsistences or persons are in the divine essence that is one and the same in number. They prove it with this reasoning:
When any two things are distinguished from each other by logic or definition, no contradiction is involved if when one is multiplied, the other is not multiplied. For then to be multiplied and not to be multiplied, to be one and not to be one—these seem to be contradictory not in the single manner that is required for a contradiction. Rather, this falls into two different manners. For those things are not contradictory that are attributed to one thing in different manners but only when that thing is said to exist and not exist in precisely the same manner. Therefore because essence and subsistence [i.e., hypostasis, person] are distinguished by logic as a thing and its mode—for subsistence is a mode of existing of itself, while essence is the nature itself existing in that mode—thus it happens that no contradiction is involved when subsistences are multiplied without multiplying their nature and, conversely, when natures are multiplied without multiplying their subsistences. By faith we acknowledge the first of these in the case of God, in whom a nature (one in number) subsists in three different subsistences. With the same faith we believe the other in the case of Christ, in whom two natures (divine and human) subsist in one subsistence of the Word.
So much for that. (See also Smiglecki, De error. nov. Arian., bk. 1, c. 18, and Fioravanti, bk. 3, c. 3.)
We readily concede that these are not contradictory in and of themselves—that God is one in essence and three in persons—for a true contradiction indicates falsity because two contradictory things can never be true at the same time. Nevertheless if we allow our reason to judge concerning this mystery, it dreams up for itself pure contradictions, for it can in no way comprehend how the hypostatic property of the Father is most really one with the divine essence in the Father yet is really distinguished from the hypostatic property of the Son (which is most really one with the divine essence in the Son). Therefore the safest thing is to understand and discuss this mystery on the basis of Scripture alone.
The arguments of the Photinians: First, Matthew 19:17: “No one is good but God alone.”
§ 99. Let us, then, pass over human reasonings, which we ought not heed in this mystery (for this mystery surpasses not only all human wisdom but even angelic reason), and let us look at the words of Scripture from which they want to prove that as there is one essence in God, so also there is only one person. (I) Matt. 19:17 and Mark 10:18: “When a certain lawyer had said to Christ: ‘Good Teacher, what good deed must I do to have eternal life?’ Christ answers him: ‘Why do you call Me good? No one is good but God alone.’ Here they note that Christ is speaking about the Deity considered in itself because He is speaking about goodness, which is an essential attribute of the Deity. Consequently, He is therefore denying that He is good because He is not God. Thus He opposes to Himself the one and only Good.”
We respond. (1) The Photinians cannot simply and completely deny goodness to the Son. John 10:11: “I am the Good Shepherd.” Wisdom 7:26: “It is the spotless mirror of the brightness of God and the image of His goodness.” Therefore they are compelled to acknowledge that Christ is saying this only in a certain manner and respect.
(2) We should not look for that certain respect in the notion that Christ does not want to be called good because He is not the true God along with the Father. We conclude this from the clear passages in which He is called “God.” What is clearer than the apostle’s word in 1 John 5:20: “This is the true God and eternal life”? Athanasius calls this testimony “written proof” in his debate with Arius.
(3) As in many other places, so also in this passage Christ is accommodating Himself to the opinion of the one who was speaking with Him. You see, we make a discourse with others in a double sense: (a) in an absolute sense, according to our mind; (b) in a relative sense, according to the mind of the other. In this passage Christ is answering not according to His own mind but according to that of the man who is asking, for he had called Christ “good” in no other sense than he would have called any teacher “good.” For this reason Christ reproves him for calling Him good if he did not believe that He is God, who is good of Himself, supremely and essentially good. (Cf. Nazianzen, Orat. 5. de theol.; Basil, Contra Eunom., bk. 4; Epiphanius, Haeres., 69; Ambrose, De fide, bk. 2, c. 1; Chrysostom, commentary on this passage in Matthew; etc. See more statements of the fathers in Jean de LaHaye, Evang. disp., c. 133, at v. 2.)
Second, John 17:3: “This is eternal life …”
§ 100. (II) John 17:3: “ ‘This is eternal life, that they know You, the only true God, and Jesus Christ, Your Son, whom You have sent.’ If the Father alone is true God, then the Son is not” (Socinus, Tract. de Deo, Christo et Spir. s., p. 6; Catech. Racov., p. 32; Transsylvani ministri, bk. 2, c. 5). We respond. (1) Some give the answer that we have here a fallacy of composition and division. The word “alone” ought not be related to the subject—as if the Father alone is called true God—but to the predicate, because the Father is the alone true God, outside of whom there is no other. The article 
and the exclusive adjective 
are prefixed not to the subject 
but to the predicate 
. (An exclusive adjective of the subject is that which excludes all other subjects from participating in the predicate. An exclusive word of the predicate is that which places a sign of exclusion between subject and predicate and excludes all other predicates from the same subject. From this comes the rule: An exclusive word of the subject does not exclude those things that are the same in individual essence with the subject.) They confirm this from the sequence of the Greek text and from the Syriac paraphrase “that they may know You, who are the only God of truth (
),” that is, besides whom no one is true God.
(2) Some teach that the words should be construed in this way: 
, “that they may know the only true God who is opposed to imaginary and false gods, namely, You and Jesus Christ, whom You have sent.” They declare that this reading can be confirmed by the article 
.
(3) We respond on the basis of the rule that the holy fathers hand down: that the exclusive word “alone” is not opposed to the other persons of the Godhead but to creatures and imaginary deities. When a discussion refers to something that fits any divine person according to essence, other divine persons who are of the same divine essence are not excluded. Indeed, they are included. Augustine, Contra Max., bk. 3, c. 13: “The word ‘alone’ does not exclude those persons who are of the same nature with the Father, but rather [it excludes] created things.” Cyril, Thesaur., bk. 10, c. 6: “We must necessarily take what is said—‘that they may know You, the only true God’—as [directed] against the false gods of the heathen.”
We prove this rule: (a) From the general meaning of the exclusive word. The word “alone” is not always taken simply and absolutely so as to exclude everything without exception, even what is joined with a person or thing in a certain respect, but only [to exclude] certain things. 1 Kings 12:20: “There was none that followed the house of David but the tribe of Judah alone.” Here, however, the tribe of Benjamin, which had joined the tribe of Judah, is not excluded. John 8:9: “Jesus remained in the temple alone.” Here not the woman but her accusers are excluded. Mark 6:47: “Christ was alone on land,” but here only the disciples are removed. 1 Cor. 9:6: “Or is it Barnabas and I alone who have no right?” Here the exclusive word “alone” is used to refer to Paul alone, but Barnabas is not excluded. In fact, he was associated with Paul in the work of preaching the Gospel. If Barnabas is not excluded by the word “alone” used in reference to Paul because of the unity in their work, all the more must we understand that the Son is not excluded by the word “alone” used in reference to the Father because of their unity in being [in essendo].
We must, however, come even closer. Therefore we say, (b) in this passage, the Son is not excluded from divinity. This can be established from the fact that the Son is mentioned expressly: “This is eternal life, that they may know You, the only true God, and Your Son, Jesus Christ, whom You have sent.” If eternal life is said to consist of the knowledge of someone in the same and equal manner in which it also consists of a knowledge of the Father, then that someone is true God with the Father. (If there is one spiritual and divine knowledge of them, then one divine nature belongs to them.) But eternal life is said to consist of the knowledge of Christ in the same and equal manner by which it consists of the knowledge of the Father. Therefore. The major premise is proven from 1 John 5:20, where the Son’s divinity is demonstrated from the fact that “in Him is eternal life.” VV. 11–12: “God has given us eternal life, and this life is in His Son…. He who has the Son has life.” V. 20: “This is the true God and eternal life.” The minor premise is clear from Christ’s words themselves.
(c) We prove this rule from the varied use of the exclusive particle. Scripture speaks about the Deity in two ways: (α) considered externally, namely, when it attributes deity to God alone and opposes Him to the multitude of fictitious gods; (β) considered internally, when it asserts that deity is common to the three persons of the Godhead. Wherever Scripture says that God is one, that He is God alone, that there is no one besides Him or outside of Him, there deity is considered externally, and from the deity are excluded all creatures and all invented gods. This is properly the force of the exclusive when it is used to refer to God (Deut. 32:12; 1 Cor. 8:[6]; etc.). On the other hand, when the deity is considered from within or internally [ad intra], then the exclusive plainly is being rejected. John 16:32: “I am not alone, for the Father is with Me.” John 8:16: “It is not I alone … but I and He who sent Me, even the Father,” because the Father is not “God alone” in that manner that the Son and the Holy Spirit are not one God with Him16—for the Son also is true God (1 John 5:20) and has all things that the Father has (John 16:15). Therefore whenever the Father alone is called true God, the meaning is that we should not look for another God outside the deity of the Father. However, the Son and the Holy Spirit are not outside the deity of the Father, but “the Son is in the Father” (John 14:10) and is “one with the Father” (John 10:30), obviously because He has deity communicated to Himself through being eternally begotten of the Father.
(d) We prove it from the definition of the Father. The Father here is called the true God alone. In Scripture, however, the Father is described in such a way that He is the First Person of the Godhead who from eternity begot the Son, His own image, and together with the Son breathed the Holy Spirit. Remove the divinity of the Son and you have destroyed the definition of the Father as it is given in Scripture because He who does not have the eternal Son is not the eternal Father. Therefore the word “alone” is so far from excluding the Son that He is rather included in the name of the Father Himself as a partaker with the Father of one and the same divinity. The Father is God because of the deity that He has in Himself and from Himself. The Son has the same, one deity from the Father through the eternal begetting. Therefore the Son is God too. As a result Christ declares plainly in John 5:23: “Whoever does not honor the Son does not honor the Father,” obviously because the Son is of one and the same essence with the Father.
(e) We prove it from the logic of parity. If the word “alone,” used with reference to the Father as the First Person, were to exclude the Son from sharing the divinity, surely the same word used with reference to the Son would exclude the Father from the same sharing. But the consequence is absurd. Therefore the antecedent is also absurd. Basil proves that that exclusive is used with reference to the Son on the basis of Baruch 3:[35–37]: “This is our God; no other will be compared with Him. He found the whole way to knowledge …. Afterward He appeared on earth and lived among men” (Contra Eunom., bk. 4). Because the book of Baruch is outside the canon, however, we cite another example that Cyprian presses in Ad Quirin., bk. 2, c. 6, on the basis of Isa. [43]:10–11: “I am He. Before Me no god was formed nor shall there be any after Me. I, I am the Lord, and besides Me there is no Savior.” He concludes clearly that these words apply to Christ from Isa. 45:21–23: “Was it not I, the Lord? And there is no other god besides Me, a righteous God and Savior. There is none besides Me. Turn to Me and be saved, all the ends of the earth! For I am God, and there is no other. By Myself I have sworn; from My mouth has gone forth in righteousness a Word that shall not return, because every knee will bow to Me.” In clear language, the apostle in Rom. 14:[11] refers this passage to Christ, and the situation itself shows that we should understand it as referring to Christ, who is saving (Gen. 49:18; Isa. 52:10) and is the Savior (Zech. 9:9; Luke 2:11). In fact, “there is salvation in no one else” (Acts 4:12) and in Him is our righteousness (2 Cor. 5:21). Jude 4: “Who deny our only Master, God, and Lord, Jesus Christ.” V. 25: “To the only wise God, our Savior, be glory,” etc. Here it is obvious that the words refer to Christ. 1 Cor. 2:2: “I decided to know nothing among you except Jesus Christ.” Here he is not excluding a knowledge of the Father and the Holy Spirit. He mentions Christ alone because there is no way to salvation outside of Christ. Therefore the exclusive word is used with reference to Christ because without Him there is no Savior nor God. That is, the fact that He alone is Savior and God by no means excludes the Father and the Holy Spirit but is opposed to the gods of the heathen (Isa. 45:15–16). In exactly the same way, when it is used concerning the Father, it does not exclude the Son. Matt. 11:[27]: “No one knows the Son except the Father,” that is, the Father alone; “and no one knows the Father except the Son,” that is, the Son alone. Yet the Holy Spirit is not excluded; in fact, “He searches the depths of God” (1 Cor. 2:10). In the same way we read in Mark 13:32: “Of that day no one knows, not even the angels in heaven nor the Son (clearly according to the human nature and in the state of humiliation) but only the Father.” Here the Son is not being excluded according to His divine nature and state of exaltation, as is shown elsewhere, nor [is] the Holy Spirit [excluded], who is one God with the Father and the Son. 1 Cor. 2:11: “No one comprehends the thoughts of God except the Spirit of God.” Rev. 19:12: “No one knows His name except Himself.” Nevertheless neither the Father nor the Holy Spirit is being excluded. In his commentary on Romans 8, Origen cites the words of 1 Cor. 8:6, where Christ is called “one Lord,” yet the Father is not being excluded, who is Himself Lord of all. 1 Tim. 6:15–16: “The Father is the only Potentate, the King of kings and Lord of lords, who alone has immortality,” etc. Nevertheless the Son is not being excluded, who also Himself is called “King of kings and Lord of lords” (Rev. 17:14; 19:16).
The statements of the ancients can shed some light on these foundations of our response. Hilary, De Trinit., bk. 3, p. 27:
The Son pays the honor owed to His Father when He says: “You alone are the true God.” Nevertheless the Son does not separate Himself from the true God when He adds: “and Jesus Christ, whom You have sent.” The confession of believers draws no line between the two because their hope for life is in both, nor is “true God” lacking to Him whose name follows [in the Creed]. Therefore when it says, “that they may know You, the only true God, and Jesus Christ, whom You have sent,” the indication of one sending and one sent is not meant to show a difference between the true Godhead of the Father and of the Son under any semblance of distinction or discrimination. Rather, it serves as a guide to the religious confession of them as Begetter and Begotten.
De Trinit., bk. 2: “I do not understand how for our faith He should be separated from the true God when He is not separable for our salvation …. If the one God, the Father, does not take away from Christ that He is the one Lord, then the one true God, the Father, does not take away from Christ that He is true God, because this is what accomplishes the reward of eternal life: when one true God is believed, Christ also is believed. Because Christ is united in the belief and confession of the true God, the Father, tell me, what faith is it to deny that He is true God and to say that He is a creature, because it is no faith to believe in the only true God without Christ?”
Epiphanius, Haeres., 42, p. 233: “These things are said not because the Son and the Holy Spirit are not true God but so that the human mind might be led back to the one Unity, to the one Deity, from the multitude of gods.” Basil, Epistle 141, vol. 2, p. 107: “When God is said to be ‘one’ and ‘alone’ in Scripture, this is not said to the exclusion of the Son and the Holy Spirit, but against those who, though they are not gods, are falsely called ‘gods.’ ”
Cyril, Thesaur., bk. 10, c. 6: “We cannot exclude the Son whenever the Father alone is said to exist or to do something—who alone stretches out the heavens, as the prophet writes regarding the Father. Also the voice of the Father Himself is heard: ‘I alone have stretched out the heavens.’ Nevertheless it is also clearly said of the Son: ‘By the Word of the Lord were the heavens made.’ If, then, the Son is said to have made them, though the Father is said to have created the heavens alone, it is clear that even when the Father alone is called the true God we must understand also along with Him the Son, through whom He did all things and through whom He speaks.”
Athanasius, in his debate against Arius in the Council of Nicaea, cites this example: “If one were to say: ‘Surely you must know that Constantine alone is the ruler of the land and sea and that Constantius is his son,’ here the son is not separated from an association in the sovereignty but is rather joined to it.”
Basil urges this idea: “Just as one may not conclude from the fact that the Son is said to be God, blessed over all things, that He is even greater than the Father, so also when the Father is said to be the only true God, we should not take that in the sense that the Son is being excluded” (Contra Eunom., bk. 6).
Nazianzen, Orat. 5. de theol.: “The words ‘that they may know You, the only true God’ are proclaimed to overthrow the gods who, despite the fact that they actually are not gods, are still called ‘gods.’ For the words ‘and Jesus Christ, whom You have sent’ would not be added if the words ‘only true’ were placed there to set the Son apart instead of being uttered about the Deity in common.”
Augustine, De Trinit., bk. 6, c. 9, explains “alone” with the word “one”: “We say that the Father is the one true God and the Son is the one true God and the Holy Spirit is the one true God and, at the same time, that the Father, Son, and Holy Spirit, that is, the Trinity itself, are not three true Gods but one true God.” Later he adds: “This can be the arrangement of the words: ‘that they may know You and Him whom You have sent, Jesus Christ, the one true God.’ ”
(f) We prove it from the confession of our adversaries. Although our adversaries do not acknowledge the unity of essence in the Father and the Son, yet because they teach that the Son is subordinate to the Father, therefore they teach that the exclusive used in reference to God the Father is not opposed to Christ. Socinus, Miscell., p. 273: “When the word ‘only’ and words meaning the same thing are said with reference to God, they never exclude those who are subordinate to Him.” In his response to part 1 of Smiglecki, c. 2, p. 14, Schmalz writes as follows about Matt. 4:10: “Christ is not excluding Himself when He cites these words from the Law: ‘You shall serve God alone.’ ” Socinus, Epist. ad Radecc., p. 149: “When the word ‘only’ and words meaning the same thing are spoken concerning God, they never exclude those who are subordinate to Him.”
Third, 1 Corinthians 8:6: “One God, the Father, from whom are all things.”
§ 101. (III) 1 Cor. 8:6: “For us there is one God, the Father, from whom are all things and we for Him, and one Lord Jesus Christ, through whom are all things and we through Him.”
We respond. (1) The apostle expressly calls Christ 
, “Lord,” which the Septuagint translators use instead of the Tetragrammaton “Jehovah.” Therefore when the Father is said to be “one God,” the Son is not being excluded thereby. In the same way, the Holy Spirit is not excluded when the Father is said to be “one God” and the Son “one Lord” because He Himself is called both God and Lord in 1 Cor. 12:11. The supreme and absolute Lord is also the true God. Christ is the supreme and absolute Lord because He is set in opposition to all other lords, that is, He Himself is the Lord of lords, which befits the true God alone.
(2) The word “one” does not exclude the other persons of the Godhead but excludes creatures and fictitious deities, as we gather from the preceding words: “Although there may be so-called gods in heaven and on earth—as indeed there are many ‘gods’ and many ‘lords’—yet for us there is one God.”
(3) The phrases “from whom” and “through whom” imply no inequality between the Father and the Son because [the latter] is also said regarding the Father: “For it is fitting that He from whom and through whom all things exist, in bringing many sons to glory, should confirm the author of their salvation through suffering” (Heb. 2:10); because “through Him we were called into the fellowship of His Son” (1 Cor. 1:9); and because Paul is called an apostle “through Him” (Gal. 1:1). Consequently, these phrases indicate no inequality of activity, of works, or manner of operating—for the opposite is clear from John 5:19. Rather, they indicate the order and distinction of persons, as Basil teaches in great detail in De Spiritu s., c. 8. The Photinians themselves interpret the apostle’s words in Rom. 11:[36] (“from Him and through Him and to Him are all things”) as a reference to the one true God. (Zeno in Laertius: 
They call Jupiter 
[“through”] because all things were thought to be through him.)
(4) If someone could correctly conclude that the Son is not God because the Father is called the one true God, surely with the same logic he could correctly conclude that the Father is not the Lord because the Son is called the one Lord.
Fourth, Ephesians 4:6: “One God and Father of us all.”
§ 102. (IV) Eph. 4:6: “One God and Father of us all, who is above all and through all.”
We respond. (1) The word “Father” here is not taken relatively or personally for the First Person of the Trinity but essentially for all three persons. Mal. 2:10: “Have we not all one Father? Has not one God created us?” Matt. 23:9: “You have one Father, who is in heaven.”
(2) The First Person of the Trinity is called “Father” in two respects: (a) in reference to His internal operation [operis ad intra] because from eternity He begot His Son, His image. In this sense the name “Father” is not given to the Son nor to the Holy Spirit. (b) In reference to His external work [operis ad extra] because out of His fatherly goodness He has created and still preserves all things through the Son in the Holy Spirit. In this sense the name “Father” is also assigned to the Son. Isa. 9:6: “The eternal Father.” Also, the Holy Spirit is called the “Father of the poor” in the Church’s hymn.17
(3) The apostle is so far from attacking the trinity of persons on the basis of the unity of the divine essence that he is instead pointing out the three distinct persons in this passage. For when he had said, “There is one God and Father,” then he adds, “who is above all and through all and in us all,” with which words he designates the distinct persons of the Godhead, just as he had also done in Rom. 11:36. To the Father he attributes the fact that He is “above all,” as in Rom. 11:36 all things are said to be “from Him”; to the Son, that He is “through all” because all things are said to have been made “through Him” (John 1:3); to the Holy Spirit, that He is “in all things.” Wisdom 12:1: “Your incorruptible Spirit is in all things.”
The practical use of the doctrine of the unity of the divine essence.
§ 103. Christ reveals the practical use in His prayer before His suffering (John 17:21–22) where He addresses the Father with these words: “(I pray) that they may all be one, even as You, Father, are in Me and I in You, that they may also be in Us…. The glory that You have given Me I have given to them that they may be one just as We are one—I in them and You in Me—that they may become perfectly one.” You see, though we may not be able to aspire to that utterly united essential unity that is between the Father and the Son, yet, as an example of that unity, it is proper for us also to strive for the unity of souls.
Athanasius, Orat. 4. contra Arian., p. 237: “As the Father and the Son are one in essence, so also by some likeness and rough form, while we look upon Him, we are made one with one common harmony of heart among us and with a unity of spirit.” And later: “Therefore He (the only-begotten Word) is one with His Father by nature and truly, but all of us are related [cognati] to one another and have been begotten of one man, and by the one nature of all men we are made one in affection and mind, having as our archetype and example the natural unity of the Father and the Son.” Cyril, on John, bk. 11, c. 26: “What is that manner of praying that ‘they may be one just as You, Father, are in Me and I in You, that they also be one in Us’? He is asking for the bond of love, peace, and harmony, which leads believers to so great a spiritual union that it imitates the likeness of the natural and consubstantial union in the Father, Son, and Holy Spirit.”
With serious words the apostle urges us to this unity of like-mindedness and harmony in Eph. 4:4–6, where he lists the various types of unity, all of which should invite us to that spiritual unity in Christ. [1] First is the unity of body. The apostle could have begun with that natural unity and relationship by which we all take our origin from one first parent. In this respect we are all members of one body, in reference to which Acts 17:26 says: “God made from one blood every nation of men to live upon the earth.” However, because he intends to discuss the spiritual unity in Christ, therefore he omits that natural kinship and puts the unity of body in the first place. This unity of body, however, consists not only in the fact that Christ made one body and one Church out of two peoples, Jews and Gentiles (see Eph. 2:14; 3:[6], where the Gentiles are said to be “members of the same body and fellow partakers of the promise”), but also and especially in the fact that all true believers are members of one mystical body whose head is Christ. Thus they are united in this way not only among themselves but also with Christ as their head, as the explanation is added in v. 15: “Let us in all things grow up in Him who is the head, even Christ, from whom the whole body, being compacted and joined by what every joint supplies, according to the working in the measure of every part, makes increase of the body, unto edifying of itself in love” (Eph. 4:15–16). Therefore as intimate as this union is between the members of a living body and its head, so intimate also is that union between Christ and believers, who are the members of His mystical body. (See Eph. 1:22; 5:25; Col. 1:18; etc.) Moreover, it is not right for members of one body to be at variance with each other.
[2] Second is the unity of the Spirit. The union of believers among themselves and with Christ—through which they become members of the one mystical body whose head is Christ—is created by the Holy Spirit, who is the bond of believers among themselves and with Christ. 1 John 4:13: “By this we know that we abide in Him and He in us: because He has given us His own Spirit.” You see, as the Holy Spirit is the bond of love between the Father and the Son, so also is He the bond of love between God and all in whom the Holy Spirit dwells as in His own temple. 1 Cor. 6:17: “He who is united with the Lord is one Spirit.” Just as husband and wife are one flesh because of the bond of marital unity, so God and the believing soul in whom the Holy Spirit dwells are one spirit. Cyril, op. cit.: “Having received the Holy Spirit, we are in some way united among ourselves and with God. Although Christ does distribute the Spirit of the Father and of Himself to each one of us, nevertheless the indivisible Spirit, as He is distributed to each, unites all of them in Himself and makes all of them to whom the distribution has been made to be one in Himself.” If they have one Spirit, they also have one mind.
(3) The unity of hope. Although in this life the devout have different callings and different gifts (1 Cor. 7:17), nevertheless there is one general calling for all to piety and to the service of God, also one hope of calling set forth to all in Christ, namely, eternal life. In fact, God has promised the rewards of eternal life to all who believe in Christ and persevere in true faith and the pursuit of piety. 2 Tim. 4:8: “Not only to me but to all who love His coming.” It is not fitting that those who will be victorious together in heaven should be at variance on earth.
(4) The unity of the Lord. “We all have one Lord,” but who is that? Our Savior, Jesus Christ, who in the special wording of the New Testament Scripture is called “Lord.” He is the one Lord of us all: (α) With respect to His incarnation, because He is consubstantial with all of us with respect to His assumed flesh. Eph. 5:30: “We are members of His body, of His flesh, and of His bones.” Just as Christ is consubstantial with the Father in His divine nature, so He is consubstantial with us according to His human nature. In this sense and respect, a sort of fellowship and unity of nature exists between Christ and us. Indeed, because the Word has personally united the human nature assumed from us with Himself, we are correctly said to be united with God because of the mystery of the incarnation—not that each and every human nature has been united personally with the Word but because that unique flesh assumed from Mary and taken up into the very Divinity comes in contact with us by the bond of natural recognition [naturalis cognitionis vinculo nostram attingit]. (β) He is one Lord of us all also with respect to the redemption, because with His suffering and death He has redeemed not merely a few men elected by absolute decree but the entire human race. Therefore He is the Lord of us all because He has redeemed all to be His special people, though the salutary fruit of this redemption affects only those who believe (see Matt. 1:21; Titus 2:[14]; etc.). Therefore because we are servants of the one Lord, it is not right for us to be at variance among ourselves.
(5) The unity of faith. As there is one Gospel by which we all are called to the hope of eternal life, so also one faith unites and conjoins all who believe as it is kindled by the Holy Spirit from the preaching of the Gospel. Therefore because their minds are joined together by the unity of faith, it is not proper that their wills be at variance with one another.
(6) The unity of the mysteries or of the Sacraments. The apostle says: “one Baptism.” In 1 Cor. 12:13 he says: “For by one Spirit we are all baptized into one body.” By one Baptism we are grafted into the one mystical body of Christ and receive the one Holy Spirit. Also in the Holy Supper, the second [altero] sacrament of the New Testament, the communicants are united among themselves and with Christ through their sharing of the body and blood of Christ. 1 Cor. 10:17: “For we, being many, are one bread, one body, for we all partake of the one bread.” On the basis of this principle, the devout ancients also conclude that our bodies will be raised. It is proper that those who share the same sacraments should certainly foster unity among themselves.
(7) The unity of God. As the devout truly worship one God, so also it is fitting that they express that unity with agreement of their minds and with the deed itself [i.e., in worship]. “There is one Father of us all.” It is not at all proper for children of one father in one household to be at variance.
16 That is, in whatever way the Son and the Spirit are said to not be one with the Father, this is not the manner in which the Father is said to be “God alone.”
17 That is, the sequence hymn Veni Sancte Spiritus.