22 Now all this was done, that it might be fulfilled which was spoken of the Lord by the prophet, saying, 23 Behold, a virgin shall be with child, and shall bring forth a son, and they shall call his name Emmanuel, which being interpreted is, God with us. (Matthew 1:22-23 KJV)
William Burkitt’s New Testament Commentary
Of all the prophets of the Old Testament, the Prophet Isaiah has the honor to be the first recited in the New. Here the Evangelist quotes his prophecy of Christ’s incarnation, Behold, a virgin shall be with child.
Learn thence, That the great mystery of our Savior’s wonderful incarnation was, (though darkly) revealed to the Church of God under the Old Testament.
Observe further, the name given to our Savior under the Old Testament, Emmanual, that is, God with us; God manifest in our flesh, God appearing in nature; God reconciling man to himself.
O happy and blessed union of two natures in one person! Christ is God and man united, that God and man may be reconciled.