^ exactly. People didn't just come up with the big bang because it sounded cool. They started off with evidence. Over time more evidence was discovered and the theory was changed to be consistant with that evidence. No one says the big bang is an absolute fact but there is a great amount of evidence for it. If someday we find evidence that is contradictory to the current theory, the theory will be changed or abandoned.

Some people say there is lots of evidence for God but atheist simply don't interpret that data in the same way. I would be very interested if anyone could give evidence for a single God as apposed to multiple Gods. (No the bible isn't considered evidence to us nonbelievers)