A psychology researcher has controversially claimed that stupidity is causally linked to how likely people are to believe in God.

University of Ulster professor Richard Lynn will draw the conclusion in new research due to be published in the journal Intelligence , the Times Higher Education Supplement reports.

Lynn and his two co-authors argue that average IQ is an excellent predictor of what proportion of the population are true believers, across 137 countries. They also cite surveys of the US Academy of Sciences and UK Royal Academy showing single-digit rates of religious belief among academics.

That professional skeptics don't believe in a creator is perhaps not all that surprising. Lynn argues, however, that it is their intelligence that directly gives rise to the boffinated classes' non-God-bothering tendencies. He said: "Why should fewer academics believe in God than the general population? I believe it is simply a matter of the IQ. Academics have higher IQs than the general population."

Lynn pointed out that most children do believe in God, but as their intelligence develops they tend to have doubts or reject religion. Similarly, as average IQ in Western societies increased through the 20th century, so did rates of atheism, he said.

The researchers' claims of a direct causal link have drawn criticism from others in intelligence research, who argue their conclusions are too simplistic. London Metropolitan University's Dr David Hardman said: "It is very difficult to conduct true experiments that would explicate a causal relationship between IQ and religious belief. Nonetheless, there is evidence from other domains that higher levels of intelligence are associated with a greater ability - or perhaps willingness - to question and overturn strongly felt intuitions."