6 You may perhaps be troubled by that additional remark which he makes: "In any case, however, it is hardly consistent to believe that God, the God of Christians, was born from the womb." As if we believed that the divine nature came from the womb of a woman. Have I not just quoted the testimony of the apostle, speaking of the Jews: "Whose are the fathers, and of whom, according to the flesh, Christ came, who is God over all, blessed for ever?" Christ, therefore, our Lord and Saviour, true Son of God in His divinity, and true son of man according to the flesh, not as He is God over all was born of a woman, but in that feeble nature which He took of us, that in it He might die for us, and heal it in us: not as in the form of God, in which He thought it not robbery to be equal to God, was He born of a woman, but in the form of a servant, in taking which He emptied Himself.
He is therefore said to have emptied Himself because He took the form of a servant, not because He lost the form of God. For in the unchangeable possession of that nature by which in the form of God He is equal to the Father, He took our changeable nature, by which He might be born of a virgin. You, while you protest against putting the flesh of Christ in a virgin's womb, place the very divinity of God in the womb not only of human beings, but of dogs and swine. You refuse to believe that the flesh of Christ was conceived in the Virgin's womb, in which God was not found nor even changed; while you assert that in all men and beasts, in the seed of male and in the womb of female, in all conceptions on land or in water, an actual part of God and the divine nature is continually bound, and shut up, and contaminated, never to be wholly set free.
Source: Reply to Faustus the Manichaean (New Advent)