Question: I am...wondering about Isaiah 7:14: "Therefore the Lord himself shall give you a sign; Behold, a virgin shall conceive, and bear a son, and shall call his name Immanuel."...[Didn't this have] to come true in the time of Ahaz?

Question: I am studying Isaiah and was wondering about Isaiah:7:14Therefore the Lord himself shall give you a sign; Behold, a virgin shall conceive, and bear a son, and shall call his name Immanuel.
See All...: "Therefore the Lord himself shall give you a sign; Behold, a virgin shall conceive, and bear a son, and shall call his name Immanuel." I have understood this prophecy to apply directly to Ahaz. Therefore, this had to come true in the time of Ahaz. (I also understand that this is referring to the Messiah.) How would Ahaz know who this virgin was?

Response: We always need to keep a close eye on context. The context of Isaiah:7:14Therefore the Lord himself shall give you a sign; Behold, a virgin shall conceive, and bear a son, and shall call his name Immanuel.
See All... includes the historical narrative of Ahaz, the king of Judah who was faced with an invasion from both Syria and the northern kingdom of Israel. Isaiah prophesied under the inspiration of the Holy Spirit to King Ahaz. In verses 10-11, the Lord inspired Isaiah to tell Ahaz, "Ask thee a sign of the Lord thy God; ask it either in the depth, or in the height above." What a tremendous opportunity!

Ahaz, the grandson of Uzziah, was twenty when he came to the throne of Judah. Of his reign, the writer of Scripture recorded that he "did not that which was right in the sight of the Lord his God..." (2 Kings:16:2Twenty years old was Ahaz when he began to reign, and reigned sixteen years in Jerusalem, and did not that which was right in the sight of the LORD his God, like David his father.
See All...).

To the Lord's gracious invitation, King Ahaz replies, "I will not ask, neither will I tempt the Lord." This almost sounds like a humble response until one reads Isaiah's (still under the inspiration of the Holy Spirit) rejoinder: "And he said, Hear ye now, O house of David; Is it a small thing for you to weary men, but will ye weary my God also?" This clearly indicates that Ahaz's motives for refusal were not right. As a consequence, the Lord went beyond the immediate need of deliverance for Judah and its king. "Therefore the Lord himself shall give you a sign; Behold, a virgin shall conceive, and bear a son, and shall call his name Immanuel."

The Lord is giving a prophecy so far-reaching that it offers a deliverance to the entire world. In context, the time frame of this promise goes beyond the time of Ahaz. We know this because Isaiah:7:16For before the child shall know to refuse the evil, and choose the good, the land that thou abhorrest shall be forsaken of both her kings.
See All... notes, "For before the child shall know to refuse the evil, and choose the good, the land that thou abhorrest shall be forsaken of both her kings."

Before the child born of a virgin shall grow to maturity ("know to refuse the evil, and choose the good"), the threatening nations shall have their kings removed. This would come about through the conquest and domination by another power. This prophecy could not possibly have been limited to the reign of Ahaz. Further, we have the testimony of Matthew that (speaking of Mary's miraculous conception), "all this was done, that it might be fulfilled which was spoken of the Lord by the prophet..." (Mat:1:22Now all this was done, that it might be fulfilled which was spoken of the Lord by the prophet, saying,
See All...).

There are a number of other Scriptures that go beyond their immediate time frame. Hosea:11:1When Israel was a child, then I loved him, and called my son out of Egypt.
See All... states, "When Israel was a child, then I loved him, and called my son out of Egypt." Clearly there is the historical record of Israel's slavery in and deliverance from Egypt. That would be an immediate application. Yet, the apostle Matthew, writing of Mary, Joseph, and Jesus, said that they would be "...there until the death of Herod: that it might be fulfilled which was spoken of the Lord by the prophet, saying, Out of Egypt have I called my son" (Mat:2:15And was there until the death of Herod: that it might be fulfilled which was spoken of the Lord by the prophet, saying, Out of Egypt have I called my son.
See All...). Bible doubters and skeptics have sought to discredit Matthew's application of this prophecy, as (to their preconceived ideas) Hosea:11:1When Israel was a child, then I loved him, and called my son out of Egypt.
See All... is speaking of Israel in Egypt only. Yet, we see that is not true.

Consequently, we cannot say that what Isaiah was speaking under the inspiration of the Holy Spirit was limited to Ahaz alone. We have noted Isaiah:7:16For before the child shall know to refuse the evil, and choose the good, the land that thou abhorrest shall be forsaken of both her kings.
See All..., which in context furnishes details for a fulfillment that simply did not happen in the time of Ahaz.