The best known Messianic prophecy -- even if not it’s certainly up there -- is Isaiah’s promise to King Ahaz: “Therefore the Lord himself will give you a sign: The virgin will conceive and give birth to a son, and will call him Immanuel” (Isaiah 7:14). Isaiah’s words had an immediate application: before the young maiden’s son was very old, Israel’s enemy, Assyria, would be defeated.
The Gospel writers understood the greater meaning of the prophecy: “She [Mary] will bear a son, and you shall call his name Jesus, for he will save his people from their sins. All this took place to fulfill what the Lord had spoken by the prophet: ‘Behold, the virgin shall conceive and bear a son, and they shall call his name Immanuel’ (which means, God with us)” (Matt. 1:21-23). And Luke: “The angel answered, ‘The Holy Spirit will come on you, and the power of the Most High will overshadow you. So the holy one to be born will be called the Son of God’” (Luke 1:35).
“’God with us’—’tis eternity’s sonnet, ’tis heaven’s hallelujah, ’tis the shout of the glorified, ’tis the song of the redeemed, ’tis the chorus of angels, ’tis the everlasting oratorio of the great orchestra of the sky. “God with us.” (Charles Spurgeon). For a real treat, watch this short video.
O come, O come, Immanuel,
and ransom captive Israel
that mourns in lonely exile here
until the Son of God appear.
Rejoice! Rejoice! Immanuel
shall come to you, O Israel. –8th Century Poem translated by J. M. Neale (1851)