Isaiah 7:14, in Hebrew means maiden, not virgin. Therefore, it is not a prophecy.
"Therefore the Lord Himself will give you a sign: Behold, a virgin will be with child and bear a son, and she will call His name Immanuel," (Isaiah 7:14).
Isaiah 7:14 says that a virgin will bear a son. The problem is dealing with the Hebrew word for virgin, which is "almah." According to the Strong's Concordance it means, "virgin, young woman 1a) of marriageable age 1b) maid or newly married." Therefore, the word "almah" does not always mean virgin. The word "occurs elsewhere in the Old Testament only in Genesis 24:43 (”maiden“); Exodus 2:8 (”girl“); Psalm 68:25 (”maidens“); Proverbs 30:19 (”maiden“); Song of Songs 1:3 (”maidens“); 6:8 (”virgins“)."1 Additionally, there is a Hebrew word for virgin: bethulah. If Isaiah 7:14 was meant to mean virgin instead of young maiden, then why wasn't the word used here?
The LXX is a translation of the Hebrew scriptures into Greek. This translation was made around 200 B.C. by 70 Hebrew scholars. In Isaiah 7:14, they translated the word "almah" into the Greek word "parthenos." According to A Greek-English Lexicon of the New Testament and Other Early Christian Literature,2 parthenos means "virgin." This word is used in the New Testament of the Virgin Mary (Matt. 1:23; Luke 1:27) and of the ten virgins in the parable (Matt. 25:1, 7, 11). If the Hebrews translated the word into the Greek word for virgin, then they understood what the Hebrew text meant here.
Why would the Isaiah choose to use the word almah and not bethulah? It was probably because he wanted to demonstrate that the virgin would also be a young woman. Is it still a prophecy? Of course.
______________
1. Walvoord, John F., and Zuck, Roy B., The Bible Knowledge Commentary, (Wheaton, Illinois: Scripture Press Publications, Inc.) 1983, 1985.
2. Bauer, Walter, Gingrich, F. Wilbur, and Danker, Frederick W., A Greek-English Lexicon of the New Testament and Other Early Christian Literature, (Chicago: University of Chicago Press) 1979.
