Even people with no religious affiliation distrust atheists, according to a paper published in the Journal of Personality and Social Psychology. The series of six studies also found that much anti-atheist bias stems from the belief that "atheists can't be trusted to cooperate rather than act in their own self-interest because they don't believe God is policing their behavior," says lead author Will Gervais, PhD, a psychology professor at the University of British Columbia.

In the first study, the researchers asked 351 randomly selected Americans to rank, on a scale from one to 100, how they felt about three groups: gay men, atheists and people in general. Though participants liked gay men better than atheists overall, they found gay men to be more "disgusting" than atheists, and atheists to be more "untrustworthy" than gays.

In three follow-up studies, the researchers tested liberal college students for unconscious bias. The students read a story about Richard, a man who flees the scene after backing into a parked car and later steals money out of a wallet. The students then rated which was more likely: that Richard was a teacher or that he was a teacher and an atheist.

Logically, it's more likely Richard fits just one category (teacher) rather than both (teacher and atheist.) But thanks to a cognitive quirk known as the conjunction fallacy, people will tend to say someone is more likely to belong to two categories if they think the additional category fits the person's description.

Study participants made the conjunction fallacy for Christians just 4 percent of the time, compared with 15 percent for Muslims, 42 percent for rapists and 48 percent for atheists. This shows that many people think that being untrustworthy is characteristic of atheists and rapists, but not of members of various religious groups, says Gervais. Using this technique, the researchers also found that people view Jews, gays and feminists to be more trustworthy than atheists. Of all the groups the researchers asked about, only rapists were thought to be as untrustworthy as atheists. The researchers also found that people with strong religious beliefs and those who think moral behavior is rooted in religion were the most likely to show anti-atheist prejudice.

Interestingly, 65 percent of participants in the paper's final study said they'd hire an atheist over a religious person for a waitress job, but only 33 percent said they'd hire the atheist to work in a day-care center. "There might be some situations where people prefer to hire an atheist, maybe because they are seen as uninhibited or fun or intellectual or science-minded," says Gervais.

Another study by Gervais and his colleagues, in press in Psychological Science points to a potential solution for anti-atheist prejudice: In that study, simply asking people to unscramble words such as "jury," "court" and "police" reduced their distrust of atheists.

"All we had to do was remind people that there are lots of different sources of moral behavior in the world, and many reasons to be nice and cooperative with others," he says.