Well as they need a manual to explain to them how to get through life! I THINK THAT SAY'S IT ALL REALLY!

Trick question, cut both ways. There are smart people and not so much at both sides of the fence. It's a complex subject where local variables as culture, economics, etc come into place

Don't underestimate. Don't overestimate.
Since the Dark Ages (or before?) the best education comes from the religious orders.
In fact the church was the place to send your child to be educated.
Now if you are talking about enlightenment that is different all together,
BTW, I have run across more then a few Agnostic ass hats of the lower IQ range.

It's not so much a question of intelligence, more a question of intellectual honesty.

Check the numbers of believers in the National Academy of Sciences. ?

The short answer is, you have to be intelligent to become agnostic/atheist, but being intelligent doesn't mean you're not religious; I remember reading some study that said how questioning authority is a value mostly endorsed by smarter people. So, you could say dumb people have no choice but to be religious, while smarter people can choose between being religious or not.

I think the smartest people I know are theists. Certainly the kindest people I know are.

I don't think intelligence has anything to do with it. I've seen people that span the entire spectrum from both categories. Even intelligent people can hold to wrong-headed ideas, it doesn't make them stupid. I'm reasonably intelligent, but I've held many bad ideas over the years and I just didn't realize it.

And realizing the wrongness of the god proposition doesn't make you smart. I've first hand experience with that.

See that is the confusing thing to me. I know some wonderful otherwise intelligent people who are god followers. Just can't figure it out. ?