Here is the problem with the Christian claim of a Virgin Birth: Christians start with the assumption that it happened, and then search for evidence to confirm that assumption. Let’s do something different. Let’s start with the evidence and see where it leads:
1. The first Christian writings were by Paul of Tarsus. Does Paul ever mention that Jesus was born of a virgin? No. Simply looking at Paul’s writings, we are left with the belief that Jesus was God’s Son, Jesus was the promised Messiah, and that belief in Jesus forgives sins and merits eternal life. There is no assertion that Jesus is Yahweh himself, nor that Yahweh took on the form of a human by being born of a union between a virgin female human and the Holy Ghost.
2. The next Christian writing is the Gospel of Mark. Any mention of a virgin birth? No. Any indication that the family of Jesus, including Mary, knew that he was Yahweh, or even the Son of Yahweh? No. They thought he was mad. How is it possible that the mother of Jesus assumed he was mad if she had truly received an appearance by the angel Gabriel telling her that she would bare the Son of God??
3. We have no mention by any Christian, Jew, Roman, or pagan of the alleged virgin birth of Jesus of Nazareth until the Gospels of Matthew and Luke, written in the 80’s or 90’s, according to the scholarly consensus! Wow!
God himself mates with a human female, and no one in all of Judaism bothers to record this outrageous, never-heard-of-before claim!!
So, 40-60 years after Jesus death, two anonymous authors, writing in far away lands, produce two completely different birth narratives of a virgin birth. The two stories are not compatible except by the most bizarre of harmonizations that only someone who believes that the two stories MUST be compatible would believe.
Why would Matthew, who is known for telling “whoppers” (zombies roaming the streets and three hour eclipses) write a story about Jesus being born of a virgin: Just as the other skeptic on this thread has said: To make Jesus’ birth fit with an OT prophecy, even if he has to completely invent the prophecy by twisting the original Hebrew of the OT text. Also, Christians were dealing with accusations from Jews that Jesus was illegitimate. The virgin birth involving a Holy Ghost as the father, was the best rebuttal Christians could come up with and still be able to claim that Jesus was God Incarnate. Without the virgin birth, Jesus was just a man who had been “adopted” as God’s Son, either at his birth, at his baptism, or even at his alleged resurrection.
The Virgin Birth was an invention of the early Church to plug a gigantic hole in its evolving “christology” of turning a son of God (small “s”) into God Himself.