WHO WAS CONCEIVED BY THE HOLY SPIRIT, BORN OF THE VIRGIN MARY
Here we are reminded how the Son of God became Jesus for us — that is to say , Savior — and Christ — that is to say, the Anointed One, as King to keep us and as Priest to reconcile us with the Father.
He took our flesh in order that, having become Son of man, he should make us become, with Him, sons of God.
He clothed Himself in our poverty in order to transfer to us His riches. He took upon himself our weakness in order to strengthen us by His power. He assumed our mortal condition so as to give us immortality. He descended to earth to raise us to heaven.
He was born of the virgin Mary so as to be recognized as the true son of Abraham and of David, the one who had been promised by both the Law and the prophets. He was a true man, like us in everything, with the single exception of sin. He was tempted in line with all our weaknesses, thus learning to have compassion on them.
Nonetheless, He was Himself conceived in the womb of the Virgin, by the marvelous and inexpressible power of the Holy Spirit, so as to be born without being tainted by any fleshly corruption, but sanctified by sovereign purity.
John Calvin, Truth For All Time, pp. 38-39