Science!
Atheists are more intelligent than religious people, say researchers | The Independent [independent.co.uk]
It is interesting that there is a correlation. If you arrived to Atheism by logic, it makes sense.
I’m not at all surprised. It takes especially courageous, perceptive, assertive people to throw off the religious dogma that they were taught as children and declare themselves to be atheists.
On the other hand, a large portion of humanity has no interest in religion one way or the other and hardly know what an atheist is. Apparently in order to be a proper atheist you have to either be educated and brought up in that tradition, or you have to be put through the fire of religious indoctrination so you’ll have something to throw off.
If I change my designation to “atheist” will I gain IQ points?