Having a belief in something, in and of itself, doesn't necessarily mean the believer is mentally ill (although there was, interestingly, one study put out a couple months ago that links belief in a hateful God to mental illness). As for IQ tests, haven't they already been proven to be one of the worst ways of measuring "intelligence" in groups, be it race, religion, or otherwise? Sorry, but the more I read this bunk, the more skeptical I become of its inherent value. Both sides are guilty of abusing and misinterpreting studies to suit their own (often hateful) agenda, and this article is nothing new.
I'm not familiar with this, can you give me a quick recap?
As for the mental illness thing, anectdotally I remember atheist PZ Myers asked his readers to take the AQ test and the results were considerably higher than the norm; there might be other factors at play there though.
