53 out of 63 research studies found that belief correlates negatively with intellignce.
I'm going to take this with a grain of salt.
If someone had done a similar survey, say 200 years ago, they would have come up with very different results.
Intelligent people are generally able to be successful in society. If the society is such that religion is important to getting ahead, then intelligent people will tend to be religious. And that's the basis for my comment about 200 year ago.
I'm taking the studies with a grain of salt, because I see it as dependent on too many factors.
Fundamentalism - the anti-American, anti-Christian branch of American Christianity