Luke 1:35

35.The Holy Ghost shall come upon thee The angel does not explain the manner, so as to satisfy curiosity, which there was no necessity for doing. He only leads the virgin to contemplate the power of the Holy Spirit, and to surrender herself silently and calmly to his guidance. The word ἐπελεύσεται, shall come upon, denotes that this would be an extraordinary work, in which natural means have no place. The next clause is added by way of exposition, and the power of the Highest shall overshadow thee: for the Spirit may be regarded as the essential power of God, whose energy is manifested and exerted in the entire government of the world, as well as in miraculous events. There is an elegant metaphor in the word ἐπισκιάσει , overshadow. The power of God, by which he guards and protects his own people, is frequently compared in Scripture to a shadow, (Psalms 17:8; Psalms 57:1; Psalms 91:1.) But it appears to have another and peculiar meaning in this passage. The operation of the Spirit would be secret, as if an intervening cloud did not permit it to be beheld by the eyes of men. Now, as God, in performing miracles, withholds from us the manner of his proceedings, so what he chooses to conceal from us ought to be viewed, on our part, with seriousness and adoration.

Therefore also the holy thing which shall be born This is a confirmation of the preceding clause: for the angel shows that Christ must not be born by ordinary generation, (29) that he may be holy, and that he may be the Son of God; that is, that in holiness and glory he may be high above all creatures, and may not hold an ordinary rank among men. Heretics, who imagine that he became the Son of God after his human generation, seize on the particle therefore as meaning that he would be called the Son of God, because he was conceived in a remarkable manner by the power of the Holy Spirit. But this is a false conclusion: for, though he was manifested to be the Son of God in the flesh, it does not follow that he was not the Word begotten of the Father before the ages. On the contrary, he who had been the Son of God in his eternal Godhead, appeared also as the Son of God in human flesh. This passage not only expresses a unity of person in Christ, but at the same time points out that, in clothing himself with human flesh, Christ is the Son of God. As the name, Son of God, belonged to the divine essence of Christ from the beginning, so now it is applied unitedly to both natures, because the secret and heavenly manner of generation has separated him from the ordinary rank of men. In other passages, indeed, with the view of asserting that he is truly man, he calls himself the Son of man, (John 5:27;) but the truth of his human nature is not inconsistent with his deriving peculiar honor above all others from his divine generation, having been conceived out of the ordinary way of nature by the Holy Spirit. This gives us good reason for growing confidence, that we may venture more freely to call God our Father, because his only Son, in order that we might have a Father in common with him, chose to be our brother.

It ought to be observed also that Christ, because he was conceived by a spiritual power, is called the holy seed For, as it was necessary that he should be a real man, in order that he might expiate our sins, and vanquish death and Satan in our flesh; so was it necessary, in order to his cleansing others, that he should be free from every spot and blemish, (1 Peter 1:19.) Though Christ was formed of the seed of Abraham, yet he contracted no defilement from a sinful nature; for the Spirit of God kept him pure from the very commencement: and this was done not merely that he might abound in personal holiness, but chiefly that he might sanctify his own people. The manner of conception, therefore, assures us that we have a Mediator separate from sinners, (Hebrews 7:26.)