Chapter X:
CHAPTER X: WHICH CONTAINS THE THIRD ARGUMENT DRAWN FROM THE OLD TESTAMENT FOR AFFIRMING THE MYSTERY OF THE TRINITY
[The third argument from the Old Testament: The promise of the Messiah.]
§ 147. We draw the third principal foundation for our position from the promise of the Messiah. In the Old Testament there were two chief parts of heavenly doctrine. The first was the Decalogue, or the doctrine of the moral law, to which the ceremonial and forensic laws are an addition. The other was the the promise of the Messiah, which Moses and all the prophets published and taught along with the Law. Isa. 8:[20]: “To the Law and to the testimony!” To these two chief parts we can suitably apply whatever is taught in the Old Testament, just as in the New Testament we refer all things to the Law and to the Gospel, that is, the proclamation of the revealed Messiah. From the Law they drew their knowledge of spiritual illness; from the promise of the Messiah, the remedy for the illness. From the Law they learned what God requires of them; from the promise, what benefits God would give them.
No one, then, should doubt that in the public assemblies of their church the Israelites also repeated the promise of the Messiah along with their teaching of the Law. Yet that promise includes the mystery of the Trinity. Therefore as often as they repeated the promise of the Messiah, by the same work they repeated by public confession the doctrine of the mystery of the Trinity. The minor premise will become clear if we consider what were the chief parts of the doctrine of the person and office of the Messiah.
§ 148. Indeed, from the prophecies of Moses, of the royal psalmist, and of the prophets, we draw the obvious conclusion: (I) The devout of the Old Testament believed that the Messiah not only would be true man in the fullness of time but was true God also in the unity of the person, because: (1) To Him are attributed truly divine names proper for God alone. Not only is He called Adonai (Ps. 110:1), Elohim (Ps. 45:[6]; Isa. 35:4), and El (Isa. 9:6), but also Jehovah (Jer. 23:5; 33:14; Hosea 1:7), Jehovah Sabaoth (Isa. 44:6, Zech. 12:[5]), etc.
(2) To Him are attributed truly divine attributes, both essential—such as eternity (Prov. 8:22; Mic. 5:2), omnipotence (“mighty God,” Isa. 9:6; “Behold, your God comes with might,” Isa. 40:[10]); omniscience (because of which He is said to be “the wisdom of God,” Prov. 8:22)—and personal: that He was begotten of the Father from eternity (Ps. 2:7; Mic. 5:2), in which respect He is called “the Son of God” (Ps. 2:7; Prov. 30:4; Isa. 9:6).
(3) To Him are attributed truly divine works, such as creation, which we showed earlier is attributed to the Son of God, the promised Messiah; the working of divine miracles (Isa. 35:4); the redemption of the human race (Isa. 63:3); the bruising of the serpent’s head (Gen. 3:15); salvation (Isa. 35:4; 45:17), for which reason He is called “the salvation of God” (Gen. 49:18; Ps. 98:3; Isa. 52:10; 62:11); justification (Isa. 53:11); the preservation of the Church against her foes (Ps. 2:9; 110:1); the raising of the dead (Job 19:25); the execution of the last judgment (Gen. 18:25; Isa. 45:23; cf. Rom. 14:10).
(4) To Him are attributed truly divine worship and glory. All the peoples and tribes of the earth are ordered to serve Him (Ps. 2:11; 72:11; Dan. 7:14), to trust Him (Ps. 2:12; Isa. 28:16), to fear Him (Ps. 2:11), to hope in Him (Isa. 11:10; 14:32), to worship and call upon Him (Ps. 22:[27]; 45:[11]; 72:11; 97:7; cf. Heb. 1:6; and Isa. 45:23; cf. Rom. 14:9). All this proves clearly the true divinity of the Messiah.
§ 149. (II) They believed that the Messiah would be born a human in the fullness of time, but at the same time they claimed with certainty that He was a subsisting person already in the Old Testament. This follows from the prior point. After all, if He is not only true man but also true God, surely He existed before His incarnation and, in fact, from eternity before the creation of the world.
We prove this in particular by going backward from the time of the Old Testament to the first origin of the world and, in fact, ascending all the way to the ultimate eternity. For the Son of God was promised as the Messiah: (1) In the days of the prophets. Isaiah saw His glory (Isa. 6:1); surely he saw the glory of one who was present and existing. John 12:41 says he sees the glory of Him as He sits upon His throne. He heard Him speak to him (Isa. 8:18; cf. Heb. 2:13; and Isa. 48:16; cf. John 18:20). Jer. 34:12: “The word of Jehovah came to Jeremiah from Jehovah.” Daniel asks the Lord to hear him “for the Lord’s sake” (Dan. 9:17). Certainly, then, already at that time the Mediator for whose sake we are heard existed. Zechariah introduces the Son of God as an Angel conversing with him. It is clear that not a created angel but the uncreated one—the Son of God—must be understood from the fact that to Him are attributed the divine name, “Jehovah” (Zech. 2:[9–11]; 4:8–9; 6:15); divine works: being master of the angels (3:4–5), sending prophets (1:14, 17), removing iniquity by His own power (3:4; etc.); divine worship ([4]:4–5, 13; 6:4); in fact, even the proper work of the Mediator: interceding for the Church (1:12). Furthermore, that prophecy—“They will look upon Me whom they have pierced” (12:10)—can be referred only to the Son of God, who one day would be crucified in His assumed nature. (Cf. John 19:37; Rev. 1:7.) Mal. 3:1 also introduces Him as speaking with him: “Behold, I shall send My messenger, who will prepare the way before My face.” (Cf. Matt. 11:10; Mark 1:2; Luke 1:76; 7:27; John 1:23; etc.)
(2) In the days of Joshua and the judges. In Josh. 5:13 there appears “a man standing before Joshua” who was not a creature but the Creator and Lord Himself, the Son of God (contrary to Bellarmine, De beatitud. sanctor., c. 13), as is clear: From His name, for He is called “Jehovah” (6:2) and “commander of the army of Jehovah,” that is, of angels, humans, and all creatures (5:14). From the attribution of divine works. He calls Himself “commander of the army of the Lord” because He had led the Israelites out of Egypt, through the wilderness, and was fighting against their enemies. He also promises to deliver Jericho into the hands of Joshua (6:2). From the reception of divine worship, for He allows the worship of adoration, which is due to God alone, to be given to Himself (5:14; Matt. 4:10). From His symbolic appearance. He is seen in human form, which He assumes temporarily. The ground on which He appeared is called “holy” because through this appearance it had been sanctified and divinely appointed for this use: that it show the place for His birth and office of teaching. The Angel who appeared to the parents of Samson was the Son of God, because He is called “Jehovah” (Judg. 13:23), He says His name is “Wonderful” (v. 13; Isa. 9:6), and Manoah was afraid He would die because He had seen God (v. 22; Exod. 33:20).
(3) In the days of Moses, because that is the Angel of the Lord who appeared to Moses in the bush (Exod. 3:2), who led the Israelites out of Egypt through the wilderness by going ahead of them in a pillar of cloud and of fire (Exod. 13:21), who cast the Egyptians into the sea (Exod. 14:19), who promulgated the Law (Exodus 19, etc.), as we showed above.
(4) In the days of Job, for he says: “I know that 
my Redeemer lives” (19:25). This Redeemer is the Son of God, who by the assumption of our flesh became our relative and our brother and has redeemed us by the right of kinship and brotherhood, which is why He is called by this name in Gen. 48:[16]; Exod. 3:8; 23:20; Isa. 63:9; etc. The same Son will also complete the work of raising the dead (John 5:28; 6:39).
(5) In the days of the patriarchs. In Genesis 18 He appears to Abraham accompanied by two angels, for the name “Jehovah” (vv. 13–14, 17) and truly divine works (vv. 10, 12, 25) are attributed to one of those three. For this reason our Savior says, “Abraham saw My day” (John 8:[56]) and “Before Abraham was, I am” (v. 58). In Gen. 31:11 He addresses Jacob and calls Himself the God to whom Jacob had made his vow (v. 13) and calls him back to the land of his fathers (same verse). But Jacob had made his vow not to a created angel but to Jehovah Himself (Gen. 28:13), and it was God who promised to recall him from Mesopotamia (v. 15). The same Son of God wrestles with him (Gen. 32:24). From Him Jacob prays for a blessing for the sons of Joseph (Gen. 48:[16]), which does not befit any created angel. (Cf. Behm, Tract. de aetern. Filii divinit., c. 36, p. 264.)
To this we can refer all the appearances in which Jehovah was seen at the time of the Old Testament in the form of a man, for He was the Son of God, the Word, the person through whom God spoke with the fathers from the beginning, the witness and interpreter of the divine will, whose “delight was with the sons of men” (Prov. 8:[31]). Therefore He wished to reveal to His beloved ones the preludes of His incarnation in those visible forms.
§ 150. (III) They believed that the Messiah, the Son of God, is a person distinct from the Father. This is clear: (1) From the name “Angel,” because He is called an Angel for this reason: because the Father sends Him to humans as Mediator and Word and He was going to be sent into the flesh in the fullness of time. But one person sends while another person is sent, and an angel is not his own ambassador. It is also clear from the name “Son” (Ps. 2:7; Prov. 30:4). He is not His own Son but the Son of the Father and a person distinct from the Father.
(2) From the description of His personal property, for He is called the Son begotten of the Father from eternity (Ps. 2:7), the “firstborn” (Ps. 89:[27]), “the reflection of eternal light, the image of God’s goodness” (Wisdom 7:26). Wisdom says that it was “with God” (Prov. 8:24).
(3) From the repetition of the name “Jehovah”: “Jehovah rained from Jehovah” (Gen. 19:24); “Jehovah preached about Jehovah” (Exod. 34:5); “Jehovah saves in Jehovah” (Hosea 1:7); etc. But if the name “Jehovah” belonged to only one person, that repetition of the name “Jehovah” could not take place.
(4) From the appropriation of work. It was foretold only about the Son of God, the promised Messiah, that He would be born of a virgin and would assume human nature in the fullness of time. Therefore in the New Testament it was obvious about Him that He was a person distinct from the Father.
§ 151. (IV) They believed that the Messiah is sent not only by the Father but also by the Holy Spirit. Isa. 48:16: “Adonai Jehovah and His Spirit have sent Me.” (Cf. John 18:20 where Christ applies to Himself the words immediately preceding: “I have said nothing in secret.”) They believed that “the Spirit of the Lord would rest upon Him,” namely, “the Spirit of wisdom and understanding, the Spirit of counsel and might, the Spirit of knowledge and fear of the Lord” (Isa. 11:2). Isa. 42:1: “Behold, My servant. I have given Him My Spirit.” Isa. 61:1: “The Spirit of the Lord God is upon Me because the Lord has anointed Me to bring the good news to the meek. He has sent Me,” etc. (Cf. Luke 4:18.) They believed that He would be anointed with the Holy Spirit “before His fellows” or beyond His fellows (Ps. 45:[7]). (Cf. Heb. 1:9.) To this pertain the statements in which the promised Savior and Redeemer of the human race is called 
[“Messiah,” “the Anointed”] (Ps. 2:2; 132:10; Dan. 9:26). He is called this because He was to be anointed with the Holy Spirit according to the human nature that He would assume in the fullness of time, etc.
From all this we conclude the following: Those who acknowledge that the Messiah is (1) true and eternal God; (2) a person before His birth from the Virgin and, in fact, subsisting from eternity; (3) a person distinct from the Father; (4) upon whom the Holy Spirit would rest—such people are acknowledging the plurality and especially the trinity of persons in the one undivided essence of the Deity. But from the prophesies of the Messiah in the Old Testament the devout of the Old Testament could have and did acknowledge those four chief parts of the doctrine regarding the person of the Messiah. Therefore they also could have acknowledged and did acknowledge the plurality and especially the trinity of persons in the one undivided essence of the Deity. There can be no doubt about the major premise unless someone wants to manufacture three gods [Tritheitas] out of them, but the very clear statements about the unity of the essence of God have freed them from this error. If anyone should make the exception that “they could not have concluded the personality of the Holy Spirit from these statements,” we send him back to the arguments that we brought out in our two preceding arguments.