@nohorn - Naomi has given you a link to "Pascals Wager" - Read it, then see how, with respect, pathetic the concept of fence-sitting "just in case" really is.
As to your original question - How exactly does believing in God explain the origin of the universe? How is "well God did it" any sort of satisfactory answer to an enquiring, open mind? And, as others have pointed out before - If we were to accept that a God did in fact create the universe, that must mean that God is an extraordinarily complex being - so who or what created God?
We should always be looking to find rational, natural answers to such big questions, because that very process of seeking answers improves us as a species. So far, every single example of creation that Theists have posed can be answered by a natural process - No supernatural element either wanted or required.
Over successive generations, humanity has gradually stripped God of the grand finery of omnipotence and omniscience, to hiding in the gaps of our scientific knowledge - And now all God has left is the fig leaf that is the first milliseconds of the creation of the universe.