“'She 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).
The famous “Sign of Immanuel” when delivered by the prophet Isaiah to King Ahaz of Judah occurred during the Syro-Ephraimite War. Tiglath-Pileser III of Assyria was rapidly expanding across the Ancient Near East when the leaders Rezin and Aram of the two small nations Syria and Israel (Ephraim) respectively joined forces to resist Assyrian amalgamation. Since Judah occupied the southern border of these two conspirator nations (and thus a potential 2nd front should Judah side with Assyria), they attempted to force King Ahaz to join their coalition against Tiglath-Pileser III.
Isaiah steps into the fray advising Ahaz to resist the pressure to join anyone, but to trust in God. Isaiah even goes so far as to offer a sign from God to confirm the promises of protection despite the apparent circumstances, but Ahaz decides to trust in his own way (calling on Assyria for costly help) and not God. Thus, Isaiah gives him the sign anyway, that a virgin would give birth to a son called Immanuel, and that by the time he knows right and wrong both Syria and Ephraim will have been conquered by Assyria. Thus, God would be with his people in the even amidst such a disaster (Elwell, 725). Jerusalem survived as foretold, but the Assyrian army would rape the land, leaving its inhabits to nearly starve due to Ahaz's trust in military alliances and not God. And it occurred just as Isaiah said. (Archeology Study Bible, 1066)1. Thus, the prophecy is immediately fulfilled with the arrival of Isaiah's newborn son via his wife in the natural way, since the Hebrew word “almah” can mean “young woman” in addition to “virgin” (Elwell, 725). This son was named ultimately Maher-Shalal-Hash-Baz (Isaiah 8:1-4) as prophetic symbolism for the Assyrian plundering (Howell, 13). Some scholars point to this different naming of the child as a second mutually exclusive sign from Isaiah, in which the name Immanuel only points to Christ and Maher-Shalal-Hash-Baz only points toward Isaiah's current day (Sailhamer, 364). However, this would mean Isaiah's “first” sign to Ahaz was basically irrelevant to his situation, since it was solely future looking and would defy Isaiah's eagerness for Ahaz to ask for a sign to confirm a decision to trust in God. It is better to see these events through the “prophetic perspective,” where the prophecy acted as a sort of double entendre so that Isaiah saw immediate future and far future events collapsed into a single vision. Thus, the arrival of Maher-Shalal-Hash-Baz was a fulfillment of Isaiah's prophecy, with the final and ultimate fulfillment through the literal virgin birth of Mary's son Jesus, who filled the name Immanuel to its full meaning. For Jesus was the epitome of “God with us,” not just near to help His people through a military and political ordeal, but to literally and then spiritually be with us “until the end of the age” (Matthew 28:20) freeing those who accepted God's “sign” from the far greater nightmares of sin and death (Howell, 13).