"Almah means young woman, not virgin"
The claim, stated fairly
Isaiah 7:14 uses almah (young woman), not betulah (virgin), and the sign was for King Ahaz in the 8th century BCE.
Every clear use of almah is an unmarried young woman, and the Jewish translators of the Septuagint chose "virgin".
Almah describes Rebekah before her marriage (Genesis 24:43) and Miriam as a girl (Exodus 2:8). The Septuagint, translated by Jews before Jesus, reads parthenos, "virgin".
The sign is addressed to "the house of David" and the child is called Immanuel. Two chapters later the promised child is called El Gibbor, "Mighty God" (9:5).
The text
14לָ֠כֵן יִתֵּ֨ן אֲדֹנָ֥י ה֛וּא לָכֶ֖ם א֑וֹת הִנֵּ֣ה הָעַלְמָ֗ה הָרָה֙ וְיֹלֶ֣דֶת בֵּ֔ן וְקָרָ֥את שְׁמ֖וֹ עִמָּ֥נוּ אֵֽל׃
14Therefore the Lord Himself shall give you a sign: behold, the young woman shall conceive, and bear a son, and shall call his name Immanuel.
WEB/WMB: Therefore the Lord himself will give you a sign. Behold, the virgin will conceive, and bear a son, and shall call his name Immanuel.
Isaiah 7:14 (Hebrew, JPS 1917, WMB)
43הִנֵּ֛ה אָנֹכִ֥י נִצָּ֖ב עַל־עֵ֣ין הַמָּ֑יִם וְהָיָ֤ה הָֽעַלְמָה֙ הַיֹּצֵ֣את לִשְׁאֹ֔ב וְאָמַרְתִּ֣י אֵלֶ֔יהָ הַשְׁקִֽינִי־נָ֥א מְעַט־מַ֖יִם מִכַּדֵּֽךְ׃
43behold, I stand by the fountain of water; and let it come to pass, that the maiden that cometh forth to draw, to whom I shall say: Give me, I pray thee, a little water from thy pitcher to drink;
WEB/WMB: behold, I am standing by this spring of water. Let it happen, that the maiden who comes out to draw, to whom I will say, “Please give me a little water from your pitcher to drink,”
Genesis 24:43 (Hebrew, JPS 1917, WMB)
5כִּי־יֶ֣לֶד יֻלַּד־לָ֗נוּ בֵּ֚ן נִתַּן־לָ֔נוּ וַתְּהִ֥י הַמִּשְׂרָ֖ה עַל־שִׁכְמ֑וֹ וַיִּקְרָ֨א שְׁמ֜וֹ פֶּ֠לֶא יוֹעֵץ֙ אֵ֣ל גִּבּ֔וֹר אֲבִי עַ֖ד שַׂר־שָׁלֽוֹם׃
5For a child is born unto us, a son is given unto us; and the government is upon his shoulder; and his name is called Pele-joez-el-gibbor Abi-ad-sar-shalom;
WEB/WMB: For a child is born to us. A son is given to us; and the government will be on his shoulders. His name will be called Wonderful Counselor, Mighty God, Everlasting Father, Prince of Peace.
Isaiah 9:5 (Hebrew, JPS 1917, WMB) · English Bibles: Isaiah 9:6
In the New Covenant
22Now all this has happened that it might be fulfilled which was spoken by the Lord through the prophet, saying, 23“Behold, the virgin shall be with child, and shall give birth to a son. They shall call his name Immanuel,” which is, being interpreted, “God with us.”
Matthew 1:22-23 (WMB)
Where scholars disagree
Almah alone does not prove virginity, and the sign also had a meaning in Ahaz's day (7:16). Messianic Jews read a near and a far fulfilment; the case rests on the whole passage (chapters 7-11), not one word.
Sources
- Septuagint, Isaiah 7:14
- Rashi on Isaiah 7:14
- Hebrew: Westminster Leningrad Codex. English: JPS 1917; World Messianic Bible (public domain).