Behold

Born for you, The Greater Moses, The Last Adam, He who fulfilled all the law and the prophets, died and was raised, ascended into Heaven and is seated at the right hand of the Father.

Now the birth of Jesus the Messiah was as follows: when His mother Mary had been betrothed to Joseph, before they came together she was found to be pregnant by the Holy Spirit. And her husband Joseph, since he was a righteous man and did not want to disgrace her, planned to send her away secretly. But when he had thought this over, behold, an angel of the Lord appeared to him in a dream, saying, “Joseph, son of David, do not be afraid to take Mary as your wife; for the Child who has been conceived in her is of the Holy Spirit. She will give birth to a Son; and you shall name Him Jesus, for He will save His people from their sins.” Now all this took place so that what was spoken by the Lord through the prophet would be fulfilled: “Behold, the virgin will conceive and give birth to a Son, and they shall name Him Immanuel,” which translated means, “God with us.” And Joseph awoke from his sleep and did as the angel of the Lord commanded him, and took Mary as his wife, but kept her a virgin until she gave birth to a Son; and he named Him Jesus. - Matthew 1:18-25

The Word of God Himself, Who is before all worlds, the Invisible, the Incomprehensible, the Bodiless, the Beginning of beginning, the Light of Light, the Source of Life and Immortality, the Image of the Archetype, the Immovable Seal, the Unchangeable Image, the Father's Definition and Word, came to His own Image, and took on Him Flesh for the sake of our flesh, and mingled Himself with an intelligent soul for my soul's sake, purifying like by like; and in all points except sin was made Man; conceived by the Virgin, who first in body and soul was purified by the Holy Ghost, for it was needful both That Child-bearing should be honoured and that Virginity should receive a higher honour. He came forth then, as God, with That which He had assumed; one Person in two natures, flesh and Spirit, of which the latter deified the former. O new commingling; O strange conjunction! The Self-existent comes into Being, the Uncreated is created, That which cannot be contained is contained by the intervention of an intellectual soul mediating between the Deity and the corporeity of the flesh. And He who gives riches becomes poor; for He assumes the poverty of my flesh, that I may assume the riches of His Godhead. He that is full empties Himself; for He empties Himself of His Glory for a short while, that I may have a share in His Fulness. - Gregory of Nazianzus, Oration 45.9

Here is something marvelous: the Son of God descended from heaven in such a way that, without leaving heaven, he willed to be borne in the virgin's womb, to go about the earth, and to hang upon the cross; yet he continuously filled the world even as he had done from the beginning! - John Calvin, Institutes of the Christian Religion

We confess, therefore, that God has fulfilled the promise he made to the fathers by the mouth of his holy prophets when, at the time appointed by him, he sent into the world his own only-begotten and eternal Son, who took the form of a servant and was born in the likeness of men. He truly assumed a real human nature with all its infirmities, without sin, for he was conceived in the womb of the blessed virgin Mary by the power of the Holy Spirit and not by the act of a man. He not only assumed human nature as to the body, but also a true human soul, in order that he might be a real man. For since the soul was lost as well as the body, it was necessary that he should assume both to save both. 
Contrary to the heresy of the Anabaptists, who deny that Christ assumed human flesh of his mother, we therefore confess that Christ partook of the flesh and blood of the children. He is a descendant of David; born of David according to his human nature; of the womb of the virgin Mary; born of woman; a branch of David; a shoot from the stump of Jesse; descended from Judah; descended from the Jews according to the flesh; of the seed of Abraham, since the Son was concerned with the descendants of Abraham. Therefore he had to be made like his brothers in every respect, yet without sin. -Belgic Confession Article 18

What article 18 of the Belgic Confession proclaims is that the eternal wisdom of God in planning to save a people for himself from a fallen mass of humanity was vividly demonstrated for us in the incarnation of the Son of God. In that event even the mind of God was made tangible in a real man, with a real human body, with a real human soul, and with a real human mother. The God who exists showed himself to be real to the world, that real people might really know their real Savior in the incarnation. This is no mere theological term, but one word that captures the essence of what it means to be Christian. - Rev. Daniel R. Hyde, With Heart and Mouth, p. 243