Some people seem to think that the virgin conception of Jesus is discounted by the fact that the verse in Isaiah, which says that “the virgin shall conceive and bear a son” (Isa. 7:14) meant, to its author, simply “the young woman will conceive and bear a son,” and the child is not, apparently, supposed to be an important personage at all--his significance seems to lie in marking the amount of time which will pass between his birth and the imminent times of plenty (“he shall eat curds and honey when he knows how to refuse the evil and choose the good” Isa. 7:15).
People “argue” that because the supposed fulfillment of the prophecy was “based on a simple linguistic mistake,” the virgin conception did not happen at all. This “argument” is not very well thought out.
It is not as though the authors of Matthew and Luke first read the verse in Isaiah, then inexplicably decided it must refer to the expected messiah, and then invented fanciful, completely fictitious, but fairly detailed accounts of the miraculous conception and birth Jesus “must have had” because of the passage in Isaiah.
Given the length and degree of detail of the conception and birth narratives, it is clear that they are not “based on” or “inspired by” Isaiah 7:14. Whether or not you accept them as historical accounts, they are clearly based on stories that were being told about Jesus. Luke doesn’t even explicitly reference Isa. 7:14.
And secondly, Matthew and Luke were not necessarily ignorant of the fact that the author of Isaiah did not mean a “virgin” but rather, a “young woman” and they did not necessarily think that the author of Isaiah knew he was referring to Jesus. And if someone had explained to them that Isaiah was not referring to Jesus’ virgin conception, but to some other person’s non-miraculous conception, they probably would have said “You’re wrong. The old interpretation of scripture is ‘outdated.’ Jesus, by his life, death and resurrection, has opened our eyes to the true meaning and fulfillment of the scriptures.”
I don’t think they would have cared what the human author of Isaiah thought he was predicting. To the Christian (at the very least, to Christians in the early church), the meaning of the Hebrew Scriptures goes beyond the intentions of the original authors.
Now, there is debate over this point in Christian circles nowadays--and even among the evangelical Fuller faculty. But I don’t know how evangelical Christians who do not advocate reading the Old Testament in light of the New can explain away the fact that within the New Testament itself it is assumed that Jesus is, in a real sense, the fulfillment of the Hebrew Scriptures, and they are incomplete without an understanding of who he is.
My personal opinion, though, is that exegetical courses on the Hebrew Scriptures ought to focus strictly on the authors’ intentions and the historical-social context in which the books were written. Theology and New Testament courses are the place to discuss how the Hebrew Scriptures find their fulfillment in Christ.