This blog post originally appeared here. I've modified it slightly for presentation here.
Along with one of my colleagues at DTS, Dr. Elliott Johnson, I teach a doctoral level hermeneutics seminar. One of the major issues we address in this class is the use of the Old Testament in the New. In other words, when New Testament authors cite Old Testament passages, what are they doing? How should we understand their interpretive process? Is there something distinctive about what they do as they interpret the Old Testament that we should identify? As you can imagine, this is a big issue for translation as well, and there is "one size fits all" solution that we can use every time.
Following is an excerpt from the NET Bible preface (edited only slightly to correct some font problems) in which the use of Isaiah 7:14 in Matthew 1:23 is discussed. I wanted to reproduce this here so you can see the difficult terrain we have tried to navigate in that translation.
This verse has seen a great deal of discussion in the history of interpretation. The text of the verse from the NET Bible is as follows:
Look, this young woman is about to conceive and will give birth to a son. You, young woman, will name him Immanuel.
The most visible issue surrounding this verse is the translation of the Hebrew word 'almah. The NET Bible uses the phrase "young woman," while many translations use the word "virgin." The arguments center upon two main points: the actual meaning of the term as it is used in Hebrew, and the use of this verse in the New Testament. There is a great deal of debate about the actual meaning of the Hebrew word. However, in the New Testament when this verse is cited in Matthew 1:23 the Greek word parthenos is used, and this word can mean nothing but "virgin." Therefore, many people see Isaiah 7:14 as a prophecy about the virgin birth with Matthew 1:23 serving as a "divine commentary" on the Isaiah passage which establishes its meaning. The interplay of these issues makes a resolution quite complex. It is the opinion of the translators and editors that the Hebrew word used in Isaiah 7:14 means "young woman" and actually carries no connotations of sexual experience, so the grammatical context of the verse in the Old Testament is in our opinion fairly straightforward. Neither does the historical context of Isaiah 7:14 point to any connection with the birth of the Messiah: in its original historical context, this verse was pointing to a sign for King Ahaz that the alliance between Syria and Israel which was threatening the land of Judah would come to nothing. The theological context of Isaiah 7:14 is also limited: it is a presentation of God's divine power to show himself strong on behalf of his people. The role or birth of the Messiah does not come into view here. So the historical and theological contexts of the verse support the grammatical: the word 'almah means "young woman" and should be translated as such. Within the book of Isaiah itself, however, the author begins to develop the theological context of this verse, and this provides a connection to the use of the passage in Matthew. In Isaiah 8:9-10 the prophet delivers an announcement of future victory over Israel's enemies; the special child Immanuel, alluded to in the last line of v. 10, is a guarantee that the covenant promises of God will result in future greatness. The child mentioned in Isaiah 7:14 is a pledge of God's presence during the time of Ahaz, but he also is a promise of God's presence in the future when he gives his people victory over all their enemies. This theological development progresses even further when another child is promised in Isaiah 9:6-7 who will be a perfect ruler over Israel, manifesting God's presence perfectly and ultimately among his people. The New Testament author draws from this development and uses the original passage in Isaiah to make the connection between the child originally promised and the child who would be the ultimate fulfillment of that initial promise. The use of Isaiah 7:14 in Matthew 1:23 draws upon the theological development present in the book of Isaiah, but it does not change the meaning of Isaiah 7:14 in its original context.