I think the problem with your theory Dave is that people do convert to and from atheism in their lifetimes. While I think some is cultural, it is nowhere near as simple as a society becoming more enlightened (in our case by science) with (it can be expressed in these sort of terms - not pointing at you here) some ill educated backward people resistant new ideas. CS Lewis has been mentioned in this thread.

On a more personal level, I'd say the most scientifically qualified person I know scientifically is a phd microbiologist. If scientific enlightenment was the sole factor, I would think he would have to be in the certainly no God camp but he is of the opinion that there is another factor/dimension/something else.