Immanuel (or Emmanuel or Imanu'el, Hebrew עִמָּנוּאֵל meaning "God is with us") is a symbolic name which appears in chapters 7 and 8 of the Book of Isaiah as part of a prophecy assuring king Ahaz of Judah of God's protection against enemy kings; it is quoted in the Gospel of Matthew as a sign verifying the divine status of Jesus.
Isaiah 7-8 
The setting is the Syro-Ephraimite War, 734 BC, which saw Judah pitted against two northern neighbours, Israel (called Ephraim in the prophecy) and Syria (also known as Aram or Aram-Damascus or Syria-Damascus). Isaiah 7:1-2 tells how the kings of Ephraim and Syria attack Jerusalem when Ahaz refuses to join them in their anti-Assyrian alliance. Ahaz wishes to ask Assyria for help, but Isaiah, at God's command, takes his son Shear-jashub (a symbolic name meaning "a remnant shall return") and assures Ahaz that the two enemy kings will not succeed (Isaiah 7:3-9). Isaiah tells Ahaz of the sign by which he will know that this is a true prophecy: a young woman will give birth to a child whom she will name Immanuel (another symbolic name, meaning "God is with us"), and the lands of the enemy will be laid waste before the child is old enough to "reject the wrong and chose the right" (Isaiah 7:13-16). Isaiah 7:17 follows with a further prophecy that at some unspecified future date God will call up Assyria against Judah: "The Lord will cause to come upon you and your people and your ancestral house such days as have not been seen since Ephraim broke away from Judah - the king of Assyria" (verse 7:17). Verses 18-25 describe the desolation that will result: "In that day a man will save alive a young cow and two sheep ... in that day every place where there used to be a thousand vines ... will be turned over to thorns and briars" (verses 21-23). Isaiah 8:1-15 continues the previous chapter: the prophet tells of the birth of another child, his own son named Maher-shalal-hash-baz (yet another symbolic name), then predicts that after Ephraim and Syria are destroyed the Assyrians will come like a river in flood to "cover the breadth of your land, Immanuel" (Isaiah 8:8).
Isaiah 7:1-8:15, although set in the time of king Ahaz, apparently dates from the reign of Ahaz's son Hezekiah some thirty years later, and its purpose was to persuade Hezekiah not to join with other kings who intended to rebel against their joint overlord, Assyria. Isaiah points to the dreadful consequences that followed for Judah's northern neighbours, the kingdom of Israel and Aram-Damascus (Syria) when they rebelled in the days of Ahaz and brought the Assyrians down on themselves. In the event, Hezekiah ignored Isaiah and joined the rebels, and the prophet's warning came true: the Assyrians ravaged Judah and Hezekiah barely escaped with his throne. A century later, in the time of Josiah, the prophecy was revised to present Ahaz as the faithless king who rejected God's promise of protection for Jerusalem and the house of David, with the result that God brought Assyria to devastate the land until a new and faithful king (presumably Josiah) would arise.
Isaiah 7-8 mentions three children with symbolic names: Shear-jashub, meaning "a remnant shall return"; Immanuel, "God is with us"; and Maher-shalal-hash-baz, "the spoil speeds, the prey hastens". Isaiah 8:18 informs the reader that Isaiah and his children are signs ("Here am I, and the children the Lord has given me. We are signs and symbols in Israel from the Lord Almighty, who dwells on Mount Zion"). The meaning of these name-signs is not clear: Shear-jashub has been variously interpreted to mean that only a remnant of Ephraim and Syria will survive the Assyrian invasion, or that a remnant of Judah will repent and turn to God, while in Isaiah 10:20-23 it seems to mean that a remnant of Israel will return to the Davidic monarchy. Maher-shalal-hash-baz is more clearly related to the expected destruction of Ephraim and Syria. As for Immanuel, "God is with us", Isaiah might mean simply that any young pregnant woman in 734 BCE would be able to name her child "God is with us" by the time he is born; but if a specific child is meant, then it might be a son of Ahaz, possibly his successor Hezekiah (which is the traditional Jewish understanding); or, since the other symbolic children are Isaiah's, Immanuel might be the prophet's own son. However this may be, the significance of the sign changes, from Isaiah 7, where Immanuel symbolises the hope of imminent defeat for Syria and Ephraim, to Isaiah 8:8, where Immanuel is addressed as the people whose land is about to be overrun by the Assyrians.
Matthew 1:22-23 
The Gospel of Matthew quotes the Immanuel prophesy from Isaiah, although it uses a Greek translation rather than the original Hebrew. It begins with a genealogy from Abraham through David to Joseph, establishing Joseph as the "son of David", the rightful heir to Judah. But verse 1:16 makes clear that Jesus is not Joseph's son, and Matthew is careful never to refer to Joseph as Jesus's father. Verses 1:18-25 turn to Mary, the future mother of Jesus, betrothed (engaged) to Joseph, but "found to be pregnant through the Holy Spirit" before she and Joseph have "come together". Joseph is about to break the engagement, but an angel appears to him in a dream and tells him of the child's divine origins, and Matthew 1:22-23 explains how this is the fulfillment of Scripture: "All this happened to fulfill what had been declared by the Lord through the prophet, who said, 'Look, the virgin will become pregnant and will give birth to a son, and they will give him the name Immanuel' - which is translated, 'God with us'".
It was common in Jewish writing of the time to reinterpret the scriptures in order to signify a new meaning. This is what Matthew has done with Isaiah 7:14: the Hebrew has the child being given the name Immanuel by "she" (presumably its mother), while the commonly-used Greek translation of the time (the Septuagint) has "you" (presumably king Ahaz, to whom the prophecy was addressed). The change from "she" or "you" to "they" allows Matthew to have Joseph give the name "Jesus" to the child, thus signalling the God-born Messiah's formal adoption into the House of David, while at the same time he is "Immanuel", God with us, the Son of God.
The gospel of Matthew was probably written in the last two decades of the 1st century, by a highly educated Jew who believed that Jesus was the promised Messiah, "God with us". At first, titles such as "Messiah" and "son of God" had described Jesus's future nature at the "parousia", the Second Coming; but very soon he came to be recognised as having become the Son of God at the resurrection; then, in Mark, he becomes Son of God at his baptism; and finally Matthew and Luke add infancy narratives in which Jesus is the Son of God from the very beginning, conceived of a virgin mother without a human father.
See also 
- Barker, Margaret (2001). "Isaiah". In Dunn, James D.G.; Rogerson, John. Eerdmans Commentary on the Bible. Eerdmans.
- Blenkinsopp, Joseph (1996). A History of Prophecy in Israel. Westminster John Knox Press.
- Brown, Raymond E.; Fitzmyer, Joseph A.; Donfried, Karl Paul (1978). "Gospel of Matthew". Mary in the New Testament. Paulist Press.
- Burkett, Delbert (2002). An introduction to the New Testament and the origins of Christianity. Cambridge University Press. ISBN 978-0521007207.
- Childs, Brevard S (1996). Isaiah. Westminster John Knox Press.
- Coogan, Michael D. (2007). "Isaiah". In Coogan, Michael D.; Brettler, Mark Zvi; Newsom, Carol Ann. New Oxford Annotated Bible. Oxford University Press.
- Duling, Dennis C (2010). "The Gospel of Matthew". In Aune, David E. The Blackwell companion to the New Testament. Wiley-Blackwell.
- Ehrman, Bart D. (1999). Jesus: Apocalyptic Prophet of the New Millennium. Oxford University Press.
- Finlay, Timothy D. (2005). The Birth Report Genre in the Hebrew Bible. Mohr Siebeck.
- France, R.T. (2007). The Gospel of Matthew. Eerdmans.
- Keener, Craig S. (1999). A Commentary on the Gospel of Matthew. Eerdmans.
- Loewe, William P. (1996). The College Student's Introduction to Christology. Liturgical Press.
- Rhodes, Ron (2009). The Complete Guide to Bible Translations. Harvest House Publishers.
- Saldarini, Anthony J. (2001). "Matthew". In Dunn, James D.G.; Rogerson, John. Eerdmans Commentary on the Bible. Eerdmans.
- Sweeney, Marvin A (1996). Isaiah 1–39: with an introduction to prophetic literature. Eerdmans.
- Sweeney, Marvin A (2001). King Josiah of Judah: the lost Messiah of Israel. Oxford University Press.
- Tremmel, Robert (2011). The Four Gospels. Xlibris Corporation.
- White, L. Michael (2010). Scripting Jesus: The Gospels in Rewrite. HarperCollins.