The recent terrorist attack in France and Islamic State beheadings make it clear that religious people can do awful things. But are they stupid?

Pundits and even some academic researchers sometimes make that leap, claiming survey data associates religiousness with a lower IQ. But this conclusion never has been the subject of scientific agreement. And critics say it relies on junk science.

An essay last month on Salon, dubbed “Religion’s smart-people problem,” cited research asserting that among the most prestigious scientists in the world, religious belief “is practically nonexistent.”

“Such facts might cause believers discomfort,” the essay concluded.

That piece followed a 2013 survey of studies claiming to show superior intelligence among nonbelievers. “Religious People Branded as Less Intelligent Than Atheists in Provocative New Study” was the take of The Huffington Post.

The reports advance a century-old academic meme that argues pews are filled with relative dullards.

But some say this conclusion is drawn from garbage-in, garbage-out studies, overinterpretation of muddled survey results or a mischaracterization of the narrower finding that, within the United States, some groups of scientists seem to have a higher concentration of atheists than the population at large.

“I don’t know of any surveys that correlate low IQ with belief in God,” said Matt Young, a physics professor at the Colorado School of Mines.

Young has written books including “Why Evolution Works (and Creationism Fails)” and “No Sense of Obligation: Science and Religion in an Impersonal Universe,” which argues that the universe is not presided over by any god or spiritual force. He is a go-to source for condemning Bible-based attacks on evolution. And he runs a blog debunking claims that creationism is a type of science.

But since at least 2007, when Young was commissioned by “The New Encyclopedia of Unbelief” to evaluate the study cited last month by Salon, he has become an irritant to atheists convinced that the religious faithful aren’t merely wrong, but feeble minded.

“Some of the extreme atheists just cannot fathom the idea that anybody with any brains might want to believe without evidence that there is some sort of purpose to the universe,” Young said. “I don’t happen to believe there is. But I can certainly understand someone being emotionally or intellectually unable to admit we are here unpurposely.”

In 1996, Washington Times reporter Larry Witham and University of Georgia historian Edward Larson published a paper in the journal Nature replicating a 1914 survey of elite scientists that found more disbelievers than believers. In a 1998 follow-up letter to Nature, the authors wrote that their study showed that science is not neutral on the question of whether God exists.

Salon ran with the conclusion, giving its Dec. 21 essay the subtitle, “Religious belief the world over has a strenuous relationship with intellectualism.

In reviewing the two studies, Young found that the 1914 work, conducted by psychologist James Leuba, was flawed because it defined believers as those who understood God as a deity expected to answer prayers – a subset of religious people. For consistency, the 1996 Nature study did not edit the 1914 study’s questions.

Even if there is a higher rate of atheism among some scientists, that does not prove religious people are unintelligent, Young said. It simply could be that fields of study that reward skepticism attract more skeptics.

“I would be hard pressed to say that all scientists are smarter than all theologians,” he said.

The Nature study was followed by a 2013 analysis of 63 intelligence-and-religion studies. Published in the Personality and Social Psychology Review, it claimed to show “significant negative association between intelligence and religiosity.”

“Intelligent people are less likely to conform and, thus, are more likely to resist religious dogma,” wrote the study’s authors, led by University of Rochester psychologist Miron Zuckerman.

The Huffington Post, Psychology Today, Ars Technica, The Independent and other publications seized on those results, in particular the conclusion that religious beliefs must be unappealing to intelligent people.

But William Briggs, a private statistical consultant and adjunct professor of statistical science at Cornell University, argued in an August 2013 essay that the study did not adhere to scientific principles of data analysis, polling or statistics. Instead, he wrote that the paper attempted to draw unified conclusions from studies conducted on populations, locations and eras that had little in common with one another.

“Data of every flavor was observed, data that should not be mixed without an idea of how to combine the uncertainty inherent in each study,” Briggs wrote. He likened the Personality and Social Psychology Review analysis to some atheists’ conviction that they have based their nonbelief on superior intelligence.

For Young, being skeptical about those arguments isn’t merely good science. It’s smart anticreationism.

“I would be less able to enlist the religious noncreationists on my side,” he said, “if all I had on my side were people who would antagonize them.”

Matt Smith is a reporter for Reveal, covering religion. Smith's two-decade career in journalism began at The Sacramento Union in California. He went on to positions at newspapers in Albuquerque, New Mexico; Twin Falls, Idaho; Fairfield, California; and Newport News, Virginia. Between 1994 and 1997, Smith covered Latin America as a reporter in Dow Jones & Co.'s Mexico City bureau. For 14 years, he was a lead columnist at Village Voice Media in San Francisco. He came to Reveal from The Bay Citizen. Smith holds a master's degree from the Columbia University Graduate School of Journalism and a bachelor’s degree in political science from Reed College in Portland, Oregon. Before his career in journalism, Smith was a professional bicycle racer. He is based in Reveal's Emeryville, California, office.