From Bart’s post Twelve Days of Christmas Day 8: Why Was Jesus Born of a Virgin in Matthew and Luke?
In Matthew’s version, Jesus is born of a virgin because this is what was predicted in the prophet Isaiah, as he explicitly states in Isaiah 1:22-23: “All this happened in order that the word spoken by the Lord through the prophet might be fulfilled: ‘Behold, the virgin will conceive and bear a son, and they will call his name Emmanuel,’ which means ‘God is with us.’” The quotation comes from Isa. 7:14.
As several readers on the blog have noted, Matthew here is quoting the Greek translation of the Hebrew Bible, which does indeed say that the woman conceiving is a PARTHENOS, a word that by Matthew’s day typically meant “woman who has never had sex.” Sometimes the word simply means “young woman.” And that is definitely what the original Hebrew of Isa. 7:14 says, where the Hebrew word for “young woman” (ALMA) is used, rather than the [Hebrew] word for “woman who has never had sex” (BETHULAH).
Why is Luke Different than Matthew?
My point: for Matthew the virgin birth principally shows that Jesus’ birth was a fulfillment of the divine plan, as revealed by the fact that up and down the line it fulfilled prophecy.
Luke has a different take. He never gives the “prophecy-fulfillment- formula” you find so often in Matthew (“this happened to fulfill what was spoken by the prophet….”). In his case the virgin birth has a completely different function. Jesus is born of a virgin because it is the Spirit of God that has made Mary pregnant, not a human being, so that in a very literal sense, Jesus is the “son of God.”
It is not clear whether Matthew agreed with Luke that the virgin birth literally made Jesus the son of God, or if Luke agreed with Matthew that the virgin birth transpired in order to fulfill Scripture. This is not a contradiction between the two accounts. But it is a very big difference. What mattered to Matthew was the fulfillment of Scripture; what mattered to Luke was the divine ancestry of Jesus. Later readers would simply combine the two accounts, as if they were saying the same thing, and then would throw in the Gospel of John which is not saying the same thing at all, and end up with the idea that Christ “was incarnate by the Virgin Mary.” I’ll say more about that in a later post.
End of Extracts from Bart’s post. The emphasis above is mine.
Isaiah chapter 7 from https://www.biblegateway.com/
NIV
14 Therefore the Lord himself will give you[c] a sign: The virgin [footnote, young women] [d] will conceive and give birth to a son, and[e] will call him Immanuel.[f]15 He will be eating curds and honey when he knows enough to reject the wrong and choose the right, 16 for before the boy knows enough to reject the wrong and choose the right, the land of the two kings you dread will be laid waste. 17 The Lord will bring on you and on your people and on the house of your father a time unlike any since Ephraim broke away from Judah—he will bring the king of Assyria.”
NRSVue
14 Therefore the Lord himself will give you a sign. Look, the young woman is with child and shall bear a son and shall name him Immanuel.[e]15 He shall eat curds and honey by the time he knows how to refuse the evil and choose the good. 16 For before the child knows how to refuse the evil and choose the good, the land before whose two kings you are in dread will be deserted. 17 The Lord will bring on you and on your people and on your ancestral house such days as have not come since the day that Ephraim departed from Judah—the king of Assyria.”
ASV
14 Therefore the Lord himself will give you a sign: behold, [c]a [d]virgin [footnote is “maiden”] [e]shall conceive, and bear a son, and shall call his name [f]Immanuel. 15 [g]Butter and honey shall he eat, [h]when he knoweth to refuse the evil, and choose the good. 16 For before the child shall know to refuse the evil, and choose the good, the land whose two kings thou abhorrest shall be forsaken. 17 Jehovah will bring upon thee, and upon thy people, and upon thy father’s house, days that have not come, from the day that Ephraim departed from Judah—even the king of Assyria.
