Although I am not very religious, I find it hard to deal with someone who doesn't believe in any supreme being at all. As I was reading some philosophy homework, I was trying to figure out how people lived before anyone believed in a god. The concept of a supreme being seems so complex and abstract to me that I cannot conceive of someone simply thinking up the idea of a god.
People thousands of years ago had it tough just to live, how did they have time to think? Another argument would be their capacity to think or learn way back in time. I don't think they were very smart at all, if most of the ancient human representations are anything close to being true. Of course, in most of these representations, the cavemen seem mystified by simple things like fire.
It seems as if maybe they automatically think of a supreme being having control of such things. So if the idea of god is somehow planted in every human, this explains the question. If it does not, then the bible seems to be the only explanation. Then people really did experience god like the bible says.