17. God Incarnate (SCG 4,27–49)
SCG 4,2–26 FREQUENTLY alludes to the Son of God, the Second Person of the Trinity, by referring to Jesus Christ. It does so because Aquinas takes Christ to be the Second Person of the Trinity. He does not think that, from eternity, the Second Person of the Trinity is a nameable human individual with physical properties. He does, however, hold that Jesus of Nazareth, whom many call “Christ,” was a human being born in time who was and remains the Second Person of the Trinity incarnate.1
Here, as with his account of the Trinity, Aquinas is drawing on what he takes to be orthodox Christian teaching. More specifically, he believes what he presumed the Council of Chalcedon to have taught in its Definition of Faith. In this text we find the following:
Following the saintly fathers, we all with one voice teach the confession of one and the same Son, our Lord Jesus Christ: the same perfect in divinity and perfect in humanity, the same truly God and truly man, of a rational soul and a body; consubstantial with the Father as regards his divinity, and the same consubstantial with us as regards his humanity; like us in all respects except for sin; begotten before the ages from the Father as regards his divinity, and in the last days the same for us and for our salvation from Mary, the virgin God-bearer, as regards his humanity; one and the same Christ, Son, Lord, only-begotten, acknowledged in two natures which undergo no confusion, no change, no division, no separation; at no point was the difference between the natures taken away through the union, but rather the property of both natures is preserved and comes together into a single person and a single subsistent being; he is not parted or divided into two persons, but is one and the same only-begotten Son, God, Word, Lord Jesus Christ, just as the prophets taught from the beginning.2
According to Chalcedon, Christ is one subject, individual, or person with two distinct natures: divine and human. Christ is truly God and truly human: God as being the Second Person of the Trinity; human as God the Son incarnate. For Aquinas, Chalcedon states the orthodox doctrine of the Trinity, though he does not think that the truth of this doctrine can be philosophically demonstrated any more than he thinks that the truth of the doctrine of the Trinity can be.
Aquinas turns to the doctrine of the Incarnation in SCG 4,27–49, which he thinks of as following on naturally from SCG 4,2–26. He writes:
Since, of course, when divine generation was dealt with above, it was said of God the Son, our Lord Jesus Christ, that some things belong to him in his divine nature, and some in that human nature by the assumption of which in time the eternal Son chose to be incarnate, it now remains to speak of the mystery of the Incarnation itself.3
As I will show in the next chapter, SCG 4,53–55 turns to the question “Was it suitable (conveniens) for the Incarnation to have taken place?” So SCG 4,27–49 is not Aquinas’s last word in the SCG concerning the Incarnation. But it amounts to a unity since its concern is with whether we can believe in the Incarnation and what we might take it to involve.
Right at the outset, Aquinas accepts that the Incarnation is a great mystery. “Among divine works,” he says, “this most especially exceeds the reason.”4 But he is convinced that the doctrine of the Incarnation as expounded by Chalcedon is faithful to Scripture both with respect to what it says of Christ as God and with respect to what it says of Christ as human. So in SCG 4,27 we find the following, which will give you a sense of how biblically Aquinas takes himself to be thinking as he embarks on his discussion of the Incarnation in SCG 4.
This marvelous incarnation of God, of course, which divine authority hands down, we confess. For it says in John 1:14: “The Word was made flesh, and dwelt among us.” And the Apostle Paul says: “Who being in the form of God, thought it not robbery to be equal to God, but emptied himself, taking the form of a servant being made in the likeness of men, and in habit found as a man” (Philippians 2:6–7). This is also shown clearly by the words of our Lord Jesus Christ himself, since at times he says lowly and human things of himself, such as “The Father is greater than I” (John 14:28) and “My soul is sorrowful even unto death” (Matthew 26:38), which became him in his assumed humanity; but at times he says sublime and divine things, such as “I and the Father are one” (John 10:30) and “All things whatsoever the Father has are mine” (John 16:15), which certainly belong to him in his divine nature. Even the things which we read about what our Lord did show this. That he feared, that he was grieved, that he thirsted, that he died: these belong to the human nature. That by his own power he healed the sick, that he raised the dead. That he effectively commanded the elements of the world, that he drove out devils, that he forgave sins, that when he chose he rose from the dead: these reveal the divine power in him.5
The structure of Aquinas’s discussion of the Incarnation in SCG 4,27–49 strongly resembles the structure of his discussion of the Trinity in SCG 4,2–26. First (SCG 4,28–38), he singles out a number of authors whom he takes to be heretical and refutable with reference to Scripture (see SCG 4,4–9). Then (see SCG 4,40–49), he reflects on the Incarnation so as to say how we might think about it without talking nonsense (see SCG 4,10–25). In SCG 4,40 Aquinas notes a number of objections to belief in the Incarnation, and he replies to them in SCG 4,49. In between SCG 4,40 and SCG 4,49, he deals with questions related to what he ends up concluding in SCG 4,49. In doing all of this, he brings together arguments based both on reason and revelation, which you may now not find surprising given the way Aquinas proceeds from SCG 4,1 onward and given what he says in SCG 1,1–2 (see chapter 1, section 4 here).