Rem,
By the same token any Messiah wannabe can say that his name is Immanuel. If this passage literally meant Messiah's name would be Immanuel, than every quack in history would be getting up calling himself by that name.
Almah, so far as known, never meant "young married woman"; and since the presumption in common law and usage was and is, that ever almah is virgin and virtuous, until she is proven not to be, we have a right to assume that Rebecca and the almah of Is 7:14 and all other alamahs were virgin, until and unless it shall be proven that they were not. - R. Dick Wilson
Erudite scholar J. Gresham Machen, in "The Virgin Birth of Christ", comes to the same conclusion: "There is not place among the seven occurrences of almah in the Old Testament where the word is clearly used of a woman who is not a virgin. It may readily be admitted that almah does not actually indicate virginity, as does bethulah; it means rather 'a young woman of marriageable age.' But on the other hand one may well doubt, in view of the usage, whether it was a natural word to use of anyone who was not in point of fact a virgin."
Willis J. Beecher, in his classic essay "The Prophecy of the Virgin Mother," shares the same assessment: "The Hebrew lexicons tell us that the word almah, here translated virgin, may denote any mature woman, whether a virgin or not. So far as its derivation is concerned, this is undoubtedly the case; but in biblical usage, the word denotes virgin in every case where its meaning can e determined."
The Nature of the Sign,
In this context the sign should be understood as a highly unusual event, something only God could do, a miracle. As John Martin notes, the sign here was to be "an attesting miracle that would confirm God's word." A. Barnes concurs, stating that the sign in this context is "a miracle wrought in attestation of a Divine promise or message."
Since Ahaz refused to come up with a sign for God to perform, God Himself tells what the sign will be. It's reasonable to conclude that when God comes up with His own sign, that it would be miraculous as well.
It is also important to notice that the sign is directed to "you" (plural) and is not evidently directed to Ahaz who rejected the first offer. Isaiah said: "Hear ye now, O house of David" and it is apparent that the plural "you" in v. 14, is to be connected to its antecedent "ye" in v. 13. Since the context tells us that the dynasty of David is what is at stake in the impending invasion, it would seem proper to interpret the plural "you" as the "house of David" which is the recipient of the sign.
Now a woman becoming pregnant through natural means could not possibly fit the criteria for a supernatural sign.
John Calvin once said "What a wonderful thing did the prophet say, if he spoke of a young woman who conceived through intercourse with a man?...Let us suppose that it denotes a young woman who should become pregnant in the ordinary course of nature; everybody sees that it would have been silly and contemptible for the prophet, after having said that he was about to speak about something strange and uncommon to add 'a young woman shall conceive.'"
A closer examination of some key words in Isaiah 7:14 bears out Calvin's observation. The Hebrew word h~r~h, which is translated "conceive" in Isaiah is "neither a verb nor participle, but a feminine adjective connected with an active participle ('bearing') and denotes that the scene is present to the prophet's view". This means that the word and tense usage are similar to what the Angel of the Lord told Hagar in the wilderness centuries earlier: "Behold, you are with child, / And you shall bear a son" (Gen 16:11). In short, Isaiah 7:14 would be better translated, "Behold, the virgin is pregnant and will bear a Son." Edward Hindson comments:
It is quite obvious that the verbal time [of h~r~h] indicated here should be taken as a present tense....The concept of the time element involved is very important to the interpretation of the passage. If the word almah means "virgin" and if this almah is already pregnant and about to bear a son, then, the girl is still a virgin, even though she is a mother. Consider the contradiction if this passage is not referring to the only virgin birth in history--that of Jesus Christ. The virgin is pregnant! How can she still be a virgin and be pregnant at the same time? The implication is that this child is to be miraculously born without a father and despite the pregnancy, this mother is still considered to be a virgin. The word almah ("virgin") implies a present state of virginity just as the word h~r~h implies a present state of pregnancy. If the verbal action were in the future tense there would be no guarantee that the virgin who would (in the future) bear a son, would still be a virgin, and not a wife. But if a "virgin" "is with child" and is obviously both a virgin and a mother, we cannot escape the conclusion that this is a picture of the virgin birth.
The Greek word for virgin is parthenos, the Latin word is virgo, and one of the Hebrew words frequently used is betf~h (though whether betfl~h means "virgin" or not must be determined by the context in which it appears). R. Dick Wilson observes that "the LXX version of Is 7:14, made about 200 B.C., Matthew 1:3, from the first century A.D., the Syriac Peshitto, from the second century A.D., and Jerome's Latin Vulgate, from about A.D. 400, all render almah by parthenos (virgin) or its equivalents bethula and virgo....Since the LXX version was made in the case of.....Isaiah 200 years B.C., it is to be presumed that their rendering of alm ah by parthenos is....Is 7:14 was in their minds a justifiable rendering. So far as we have nay evidence, the citation of Is 7:1 in Matt 1:23 is thus justified by the Jewish interpretation up to the time when Matthew was written.
Or, as Henry Morris states it, "The scholars who translated the Old Testament into the Greek Septuagint version used the standard Greek word 'virgin' in translating Isaiah 7:14. So did Matthew when he quoted this prophecy a being fulfilled in the virgin birth of Christ."
B. Witherington III agrees, stating, "It is probably correct to say that if almah did not normally have overtones of virginity, it is difficult if not impossible to see why the translators of the LXX used parthenos as the Greek equivalent.
The evidence, therefore, supporting the view that the almah is Isaiah's prophecy is a young virgin woman is definitive and conclusive. No other understanding does justice to the word or its literary, social, or historical context.