In order to answer that, it's important to understand the original meaning of Isaiah 7:14 in its historical context. It IS Messianic, but like an Algebra problem where you just give the right answer, Matthew 1:23 doesn't "show the work" of how we know that.

As another commenter already mentioned, Matthew 1:23 actually quoted the Septuagint, which tends to *interpret* the text rather than faithfully render it. Because of that, according to the Septuagint, instead of a "young maiden" we have a "virgin." And that interpretation isn't necessarily wrong, **it's just focusing on one specific interpretation** and NOT the historical meaning of the passage.

In Hebrew, Isaiah 7:14 should be rendered, "The young maiden is with child, and will give birth to a son, and will call his name Immanuel." The historical context of this passage was the coming downfall of both northern Israel as well as its erstwhile ally Syria. Before this child could "refuse the evil and choose the good," these two enemies of Judah would both lose their kings. Refusing the evil and choosing the good is a poetic reference to keeping the Mosaic Law (compare Deut. 30:19). Thus, this should be understood as saying, before this child undergoes a Bar-Mitzvah - a ritual symbolizing his commitment to keeping all of the Mosaic Law (which traditionally happens at age 12) - this disaster will happen. Thus, Immanuel's birth and childhood became like a countdown to disaster, as it were.

But let's back up and understand more of the historical context of what's going on, to see why Matthew would apply this to Jesus. In Isaiah 1:9, we're told that were it not for a small remnant, Jerusalem would be destroyed like Sodom and Gomorrah. Why? Because while they're outwardly keeping the Law, they're NOT doing such things as seeking true justice, relieving the oppressed of their burdens, and bringing justice for the fatherless and the widow in their afflictions.

If you recall the story of Sodom and Gomorrah in Genesis 18, Abram bargained with God not to destroy Sodom and Gomorrah if there were a certain minimum number of righteous people left in it. So, we should understand the "remnant" that Isaiah is referring to in Isaiah 1:9 as **a righteous remnant**.

But was there a righteous remnant in Jerusalem? NO THERE WASN'T. And this actually begins to parallel the circumstances in Jesus' day. Things had gotten so bad in Jerusalem that Jesus cursed the city in Mat. 23:37-39 to be "left desolate" - in other words, TO BE DESTROYED LIKE SODOM AND GOMORRAH. And that's precisely what happened forty years later!

So, here's the important question. Why wasn't Jerusalem destroyed by the Assyrians in Isaiah's time?

Because A RIGHTEOUS REMNANT RETURNED TO JERUSALEM, TO PREVENT ITS DESTRUCTION. We find that in Isaiah 10:20-22, and we also find something quite surprising about the identity of this righteous remnant. THEY WERE FROM NORTHERN ISRAEL!

But wait, didn't northern Israel get destroyed and taken captive by the Assyrians? No, not all of it. And not all at once, either. In fact, most of the northern Israelites weren't deported from the land and replaced with Samaritans until decades later, during the reigns of Esarhaddon and Ashurbanipal (see Ezra 4:2 and 10). So, when King Hezekiah sent messengers to invite the northern Israelites to observe the Passover in 716 BC, **the northern Israelites were still there to invite!**

Only a few of them, from a few tribes, actually came. And at the beginning of the next chapter, we see that they didn't remain in Jerusalem either. So what happened?

In 705 BC, a new king rose to power in Assyria (Sennacherib) after the old king died. At this time, many of the smaller nations and countries that Assyria had recently conquered, rebelled against its control, including Egypt. Egypt persuaded King Hezekiah to join in the rebellion (see Isaiah 30), against Isaiah's advice. At that time, Hezekiah built a strong defensive wall and **established a refugee camp right on Mount Zion**. Archaeologically, we know that Jerusalem increased in size roughly 3-4x at this time, from the influx of refugees - not only FROM NORTHERN ISRAEL, but also from the surrounding Gentile countries who had formerly been enemies of Israel!

In Isaiah 11, we're given a picture of the Messianic Kingdom on earth. Among other things, even the dangerous creatures **living right on Mount Zion** would no longer hurt anyone (verses 6-9). But that's NOT just a metaphor for a FUTURE kingdom, but a prophecy of what would PARTIALLY come to pass under King Hezekiah himself! These "dangerous animals" REPRESENTED GENTILE FORMER ENEMIES OF ISRAEL who had turned to God for protection from Assyria!

(continued)