I believe in God just since I can't imagine anything other than some omnipotent being. Considering time is linear that would mean that gases and everything have ALWAYS existed. Like the Big Bang Theory, what came before all of that? Implying that everything has always existed makes no sense to me. Whatever the original thing to exist was, it must have had a beginning. It couldn't have just be created on its own without some "help". For example's sake, let's say hydrogen was the first thing to EVER exist. What made it? If NOTHING existed before it, how did it suddenly just pop into being? And yes I understand you could make the argument, "What created God then?" But since God is omnipotent, well that kind of explains itself. I'm not saying the Christian God is the actual being that created everything, I just follow it since it is more realistic then any other religion.
It took me a long-ass time to come to that conclusion, though it is the best I have to offer for the reasoning behind a God.