You got a problem, take it up with the Gospel of Matthew, brah
Ok, will do!
As I said in my first post on this thread, there are all kinds of concerns with the translation and usage of the "born of a virgin" prophecy. I'll elaborate a bit on them here.
First off, yes indeed, the LXX (Greek translation) does use "parthenos" or "virgin" in the Isaiah passage. However, this is an incorrect translation from the Hebrew. The Hebrew reads "almah" or "young woman". By contrast, the word for "virgin" in Hebrew is "bethulah". If the author of Isaiah had meant "virgin", he'd have used "bethulah", and not "almah".
Since the author of Matthew only had access to the LXX, it makes sense that he'd think it said "virgin". However, the fault there lies with the translators of the LXX.
I do fault the author of Matthew with the usage of that Isaiah passage altogether, though. If you read the whole Isaiah passage in context, it's clear it has nothing to do with Jesus:
Isaiah 7:1-17 (New Jerusalem Bible)
Yahweh spoke to Ahaz again and said: Ask Yahweh your God for a sign, either in the depths of Sheol or in the heights above.
But Ahaz said, I will not ask. I will not put Yahweh to the test.
He then said: Listen now, House of David: are you not satisfied with trying human patience that you should try my Gods patience too? The Lord will give you a sign in any case: It is this: the young woman is with child and will give birth to a son whom she will call Immanuel. On curds and honey will he feed until he knows how to refuse the bad and choose the good. Before the child knows how to refuse the bad and choose the good, the lands whose two kings are frightening you will be deserted. Yahweh will bring times for you, your people and your ancestral House, such as have not been seen since Ephraim broke away from Judah (the king of Assyria).
Jerusalem, of which Ahaz was king centuries before Christ, was besieged by the tribes of Ephraim and Judah. God is giving Ahaz a promise: that he would rescue Jerusalem. God is giving Ahaz a timeline: before the young woman who is already pregnant gives birth to a son, and that son learns to tell right from wrong. It simply doesn't make sense that Jesus would be the fulfillment of this promise -- the siege would be long over! Many scholars think the "young woman" referred to may have been Ahaz's own wife.
As I said above, it was a common and acceptable practice in NT-times to take OT passages out of context and use them to give divine credence to what the current author is trying to say. In fact, you can take almost any OT quote in the NT, read it in its context, and be quite surprised and/or confused. But if the author of Matthew had written the book today, his wrist would be slapped pretty solidly.
Take that, Gospel of Matthew! *snap!*
