OK, you atheists. Here is my challenge to you.
You say that we Christians have no "proof" that there is a God. In a sense, that is true. Scientific "proof" for the existence of God may not exist (I think that is debatable, but for the sake of the argument, let's assume that it is true), at least not to your satisfaction. Yet, I would say to you that you do not have proof that God doesn't exist either. And I would say to you that it is more rational to believe in the existence of God with the caveat that even though it is more rational, I do think that a belief in God requires "a leap of faith."
Why do I think it is more rational to believe in a God? There are too many things for which atheists have no real explanation which a belief in God does explain:
I do not believe that atheists have any valid basis for ethics or morality.
I do not believe that atheists can really explain the origin of the world. How does something come from nothing? If you believe in the primordial soup, where did the primordial soup come from? If you believe in the Big Bang, where did the matter come from that went bang?
I do not believe that atheists can explain the origin of the sensation pain. Or for that matter, I do not believe that an atheist can explain the origin of love. How can the sensations of pain or love be derived via natural selection?
Atheists challenge Christians to prove that God exists. Well, I would ask you to put the shoe on the other foot. My challenge to you is, "What is your best argument that God does not exist?" Or put another way, "Why do you believe it to be more rational to be an atheist?"