I find it very interesting that Matthew draws on so much Old Testament prophecy to tell the story. Here, he quotes Isaiah 7:14 and links it to Jesus’ birth. I can’t imagine anyone at the time of Isaiah had the slightest clue what these words would later mean.
At the time, King Ahaz (king of the southern kingdom of Judah) was scared to death that Israel and Syria would gang up against him. The Lord tells Isaiah to tell Ahaz not to worry about it. It’s all take care of. In fact, God even offers to give Ahaz a sign to confirm the promise. Who wouldn’t jump on an offer like that? Imagine being able to get a sign from God so you could be absolutely sure.
Ahaz replies, “I’ll pass. I will not put the Lord to the test.” What? Are you kidding? God says, “Fine, but you are getting a sign anyway. ‘The virgin will conceive and bear a son, and shall call his name Immanuel.'” The promise then goes on to assure Ahaz that before the boy is very old, the two enemies you are so worried about will amount to nothing.
In chapter 8, Isaiah and his wife indeed have a son and events are set in motion. But the ultimate fulfillment of this prophecy will come later when Mary is found to be with child by the Holy Spirit.
Even though the child is named Jesus, over the years many people would conclude that he was much more than just a man. Indeed, they could tell that all the the fullness of God was in Him. Like when he calmed the storm (Matt. 14:33), when he died and the earth shook (Matt. 27:54), when he reveals that he knows everything about Nathanael (John 1:49), before he raises Lazarus (John 11:27),
If you had a blank check like Ahaz, what kind of a sign would you ask for? Or would you be afraid to ask at all?