Is "original sin" a christian theology?

Actually, I think the sin theology was derived from the Jews, and the early Christians probably borrowed (and adapted or modified) the idea of original sin from Judaism. I have come to see the bible as a collection of myths borrowed from various ancient cultures, and somewhere along the way thousands of years ago, the sin concept was probably borrowed by the Jews from some of the ancient traditions that revolve around sin, atonement and sacrifices.

Until the day Jesus arrived in the scene, the Jews were still hung up about sin and sacrificial system. The Pharisees especially looked down on others as sinners. Although I have come to see Jesus as a mythological character, I do see his purpose in helping people to see themselves not as sinners but beloved children of God. He told them the kingdom of God is within them. If they were sinners, then this statement makes no sense. The fact that the kingdom of God is in us means we are all beloved and innocent children of God. While Jesus have used the term sinner in his parables, I believe he was only using their lingo to speak their language. But essentially Jesus wanted everyone to know that we and the Father are one, and we are already blameless and without spot, wrinkle or any such thing.