OK, let's try it from a different angle.
I have a friend who's an atheist. He's willing to consider becoming a Christian. He comes to me and says, "I've got a problem. I can accept that Jesus is God and died for my sins, but I've been reading Luke, and if Genesis is an allegory like so many of you Christians say it is, it looks like God is descended from someone who doesn't exist? Can you explain that?"
What do I say to this guy, Buck? His soul's on the line, so what do I say to, you know, make Christians look smart?
I think I see what the problem is here - your using allegory and historical in the same thought - he may not be able to process that.