There are two sides of the brain. The left brain rational and the side where written/spoke language is processed. Since this is the basis for eduction, one would expect the left brainers would be better trained by the left brained education system. Atheism could claim more intelligence in the left brain. Religion is more right brained which processes data differently. The right brain is more 3-D or spatial, while the left brain is 2-D. Written/spoken language is not processed by the right brain, so this side is not well trained by social education beyond religion, so right brain proficiency is not as clear cut. But since religion makes more use of the right brain, the most intelligent 3-D thinkers tend to be more religious.