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.
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.) 