from
http://kspark.kaist.ac.kr/...Intelligence%20&%20religion.htm
I'm not going to into it but numerous studies have shown a correlation between intelligence and lack of reliigious belief... Now if we look at the conclusion from the above link:
The consensus here is clear: more intelligent people tend not to believe in religion. And this observation is given added force when you consider that the above studies span a broad range of time, subjects and methodologies, and yet arrive at the same conclusion.
Why does this correlation exist? The first answer that comes to mind is that religious beliefs tend to be more illogical or incoherent than secular beliefs, and intelligent people tend to recognize that more quickly. But this explanation will surely be rejected by religious people, who will seek other explanations and rationalizations.
A possible counter-argument is that intelligent people tend to be more successful than others. The lure of worldly success and materialism draws many of these intellectually gifted individuals away from God. After all, who needs God when you (apparently) are making it on your own?
However, this argument does not withstand closer scrutiny. Most of the studies outlined above describe the religious attitudes of students, who have yet to enter the working world, much less succeed in it. Some might then argue that the most intelligent students are nonetheless succeeding in school. But "success" in school (for those who may have forgotten!) is more measured in terms of popularity, sports, physical attractiveness, personality, clothes, etc. Grades are but one of many measures of success in a young person's life -- one that is increasingly becoming less important, as many social critics point out.
And here is the kicker, which I think is the probably the most reasonable explanation for non-belief in god. THIS DOES NOT mean that there aren't plenty of intelligent people who believe in god(s) however.. it just means that the more intelligent you are the less likely you are to believe in god.
The simplest and most parsimonious explanation is that religion is a set of logical and factual claims, and those with the most logic and facts at their disposal are rejecting it largely on those grounds.
I think that is a pretty simple explanation