keep this in mind:
Paul, the earliest New Testament author, never mentions the virgin birth. For someone who we rely upon for much of Christian theology, it is an odd omission. Paul refers to Jesus’ birth twice (Rom 1:3; Gal 4:4) and never says he was born of a virgin or of different means than anyone else. You’d think that would be important.
The virgin birth is also not in Mark, the earliest gospel, or in John, the only other gospel not based on Mark. Why is such an important story left out of all the early sources? Probably because it hadn’t been made up yet.
Why would the story be made up? Perhaps to fulfill an old prophecy of a virgin birth, which the Gospel of Matthew cites:
Behold, the virgin shall conceive and bear a son, and shall call his name Immanuel. (Isaiah 7:14)
Some scholars say “virgin” was a mistranslation in the Septuagint (the Greek translation the gospel writers used), and should have been translated “young woman.” That means the story might have been based on a mistranslation!
It seems likely the virgin birth was created to boost the authority of Christianity through prophecy and compete with rival gods who were born of virgins.
When I was younger I used to love to trot this out to my Christian pals just to see how red they got in the face.
I am a little less combative these days, but it is still something that I like to introduce into the conversation once in awhile.
You know just to keep everybody on their toes.