If you are a true follower of Jesus Christ, then truth be told that faith is absolutley the only thing you need. But fact is, we are people to. It is very reassuring when we can believe in something that is scientifically proven. The bible says to be in this world, but not of this world. So that although we strive to be Christlike, we are still flesh. We still are sinful. And proving God is a way to assure the half hearted Christians of Gods existence.