“It's no easier to believe in God than it is to believe in Santa Claus; the former is just more customary”.
Comparing Santa Claus to God is like comparing a tiny marble to a universe.
So what do you believe? What would cause this tiny little marble to expand to an astronomical size in just a trillionth of a second? I believe the best explanation is “And God said, Let there be light: and there was light.”
I believe the truth: No one has a clue.