Chapter 39.--Not Everything that is Born of Another is to Be Called a Son of that Other.
We need not therefore take for granted, that whatever is born of a thing is forthwith to be declared the son of that thing. For, to pass over the fact that a son is born of a man in a different sense from that in which a hair or a louse is born of him, neither of these being a son; to pass over this, I say, as too mean an illustration for a subject of so much importance: it is certain that those who are born of water and of the Holy Spirit cannot with propriety be called sons of the water though they are called sons of God the Father, and of the Church their mother. In the same way, then, He who was born of the Holy Spirit is the Son of God the Father, not of the Holy Spirit. For what I have said of the hair and the other things is sufficient to show us that not everything which is born of another can be called the son of that of which it is born, just as it does not follow that all who are called a man's sons were born of him, for some sons are adopted. And some men are called sons of hell, not as being born of hell, but as prepared for it, as the sons of the kingdom are prepared for the kingdom.
Chapter 40.--Christ's Birth Through the Holy Spirit Manifests to Us the Grace of God.
And, therefore, as one thing may be born of another, and yet not in such a way as to be its son, and as not every one who is called a son was born of him whose son he is called, it is clear that this arrangement by which Christ was born of the Holy Spirit, but not as His son, and of the Virgin Mary as her son, is intended as a manifestation of the grace of God. For it was by this grace that a man, without any antecedent merit, was at the very commencement of His existence as man, so united in one person with the Word of God, that the very person who was Son of man was at the same time Son of God, and the very person who was Son of God was at the same time Son of man; and in the adoption of His human nature into the divine, the grace itself became in a way so natural to the man, as to leave no room for the entrance of sin. Wherefore this grace is signified by the Holy Spirit; for He, though in His own nature God, may also be called the gift of God. And to explain all this sufficiently, if indeed it could be done at all, would require a very lengthened discussion.
Chapter 41.--Christ, Who Was Himself Free from Sin, Was Made Sin for Us, that We Might Be Reconciled to God.
Begotten and conceived, then, without any indulgence of carnal lust, and therefore bringing with Him no original sin, and by the grace of God joined and united in a wonderful and unspeakable way in one person with the Word, the Only-begotten of the Father, a son by nature, not by grace, and therefore having no sin of His own; nevertheless, on account of the likeness of sinful flesh in which He came, He was called sin, that He might be sacrificed to wash away sin. For, under the Old Covenant, sacrifices for sin were called sins. [1159] And He, of whom all these sacrifices were types and shadows, was Himself truly made sin. Hence the apostle, after saying, "We pray you in Christ's stead, be ye reconciled to God," forthwith adds: "for He hath made Him to be sin for us who knew no sin; that we might be made the righteousness of God in Him." [1160] He does not say, as some incorrect copies read, "He who knew no sin did sin for us," as if Christ had Himself sinned for our sakes; but he says, "Him who knew no sin," that is, Christ, God, to whom we are to be reconciled, "hath made to be sin for us," that is, hath made Him a sacrifice for our sins, by which we might be reconciled to God. He, then, being made sin, just as we are made righteousness (our righteousness being not our own, but God's, not in ourselves, but in Him); He being made sin, not His own, but ours, not in Himself, but in us, showed, by the likeness of sinful flesh in which He was crucified, that though sin was not in Him, yet that in a certain sense He died to sin, by dying in the flesh which was the likeness of sin; and that although He Himself had never lived the old life of sin, yet by His resurrection He typified our new life springing up out of the old death in sin.
[1159] Hos. iv. 8
[1160] 2 Cor. v. 20, 21