On the Incarnation, Book 6
Born in Time, Yet Lessened in Nothing
For his coming of the flesh and in the flesh has to do with his birth and involves no lessening in him: he was simply born, not changed for the worse. For though he took the form of a servant while still remaining in the form of God, the weakness of his human make-up had no effect on his nature as God. While the power of his deity remained whole and unimpaired, all that took place in his human flesh was an advancement of his manhood and no lessening of his glory. For when God was born in human flesh, he was not born in it in such a way as not to remain divine in himself, but so that, while the Godhead remained as before, God might become man.
So Martha, while she saw the man with her bodily eyes, confessed him by spiritual sight to be God, saying, “Yes, Lord, I have believed that you are the Christ, the Son of the living God, who has come into the world.” So Peter, through the Holy Spirit’s revelation, though outwardly he saw the Son of Man, proclaimed him to be the Son of God, saying, “You are the Christ, the Son of the living God.” So Thomas, when he touched the flesh, believed that he had touched God, saying, “My Lord and my God.” For they all confessed one Christ only, so as not to make him two.
Believe him, then, and believe in this way: that Jesus Christ, the Lord of all, both the only Son and the firstborn, is both the creator of all things and the preserver of human beings, and that the same person is first the maker of the whole world and afterward the redeemer of mankind. Still remaining with the Father and in the Father, of one substance with the Father, he did (as the apostle says) “take the form of a servant, and humble himself even to death, the death of the cross”; and (as the creed says) he “was born of the Virgin Mary, crucified under Pontius Pilate, and was buried. And the third day he rose again according to the Scriptures, and ascended into heaven, and will come again to judge both the living and the dead.”
This is our faith; this is our salvation: to believe that our God and Lord Jesus Christ is one and the same before all things and after all things. For, as it is written, “Jesus Christ is yesterday and today and the same forever.” “Yesterday” signifies all past time, in which, before the beginning, he was begotten of the Father. “Today” covers the time of this world, in which he was born a second time, of the Virgin, suffered, and rose again. And the words “the same forever” denote the whole boundless eternity to come.