I just read an interesting article here which claims that those of us who are religious (sic) are less intelligent than those who are atheists. I recommend that you read it. It claims to have compiled data from numerous surveys over the last 40 - 50 years and out of some 63 studies have determined that only ten show that people of faith are more intelligent and the rest show that those without faith are superior in intelligence.
The first flaw in this so called scientific study is that they do not define religious activity or faith. The broad definition and broad spectrum of religious activity is not addressed so we of the Christian faith do not know where we stand in light of the millions of religious folks around the world, all of whom practice some sort of ritual, or have some sort of religious belief system. I do not want to be lumped together with some primitive culture who worships the moon, or some witch coven that casts spells, and yet it is in the broadest way, all religion. I would go so far as to say that atheism is also a religion, but that presents another problem for the survey.
Another observation is that there are different categories and levels of intelligence. This is not addressed in the survey nor does it state that simple IQ was the criteria.
Let us say for arguments sake that the survey is accurate and it was based on IQ. I would suggest that the higher the intelligence of an individual, the higher they would go in their formal education, the better their career would be, the higher their income and the better their confidence and self-assurance. These are just the people who tend to be self-sufficient and feel they can depend on their income, their status, and their degrees and education to get them anywhere in life they need to be. These are exactly the kinds of people who do not look outside themselves for answers and perhaps do not question the big issues in life. They do not need to, in fact discovering that there is a God would be counterproductive to their own agendas.
As I delved a little further into this study, I discovered that the difference in intelligence between the two categories of people, where they did use IQ, is a mere 6 points. In the study of IQ, a 1-6 point difference would put the two subjects in the same category of intelligence. This then becomes 'splitting hairs'.
Anecdotally, I would say some of the most faith-filled people that I personally know, are highly intelligent. One could also argue that some of the greatest scientists over the centuries have had a strong faith in God.
Neither groups, however, should get too defensive or haughty about this study. In the end, we will all know, or not know, the reality of God. And that is a fact.