The angel answered her, "The Holy Spirit will come on you, and the power of the Most High will overshadow you. Therefore also the holy one who is born from you will be called the Son of God.
therefore also that holy thing which shall be born of thee shall be called the Son of God. The human nature of Christ is here called a "thing"; for it was not a person; it never subsisted of itself, but was taken at once into union with the person of the Son of God, otherwise there would be two persons in Christ, whereas he is God, and man, in one person; and it is said to be "holy", being free from that original pollution and sin, in which all that descend from Adam, by ordinary generation, are conceived, and brought forth; and is, moreover, said to be born of a virgin, "of thee", or "out of thee". Christ's flesh was formed out of the Virgin's; he took flesh of her; his body did not descend from heaven, or pass through her, as water through a pipe, as some heretics of old said: nor did his human nature, either as to soul or body, pre-exist his incarnation; but in the fulness of time he was made of a woman, and took a true body of her, and a reasonable soul, into union with his divine person; and "therefore should be called the Son of God": not that he was now to become the "the Son of God"; he was so before his incarnation, and even from all eternity; but he was now to be manifested as such in human nature: nor does the angel predict, that he should, for this reason, be called the Son of God; for he never was, on this account, so called, either by himself, or others: nor is the particle, "therefore", causal, but consequential: the angel is not giving a reason why Christ should be the Son of God, but why he should be owned, and acknowledged, as such by his people: who would infer, and conclude from his wonderful conception and birth, that he is the "Emmanuel", God with us, the child that was to be born, and the Son given, whose name should be Wonderful, Counsellor, the mighty God, c. Isaiah 7:14. Moreover, the word, "also", is not to be overlooked and the sense is, that seeing that human nature, which should be born of the virgin, would be united to the Son of God, it likewise should bear the same name, being in personal union with him, who was so from all eternity.