Both religious people and atheists intuitively assume that the perpetrators of extreme immoral actions, such as serial murder, are probably atheists, suggests a paper published online in Nature Human Behaviour this week. The study finds that this prejudice against atheists exists in most of the 13 countries studied, both religious and secular. It suggests that, even though overt religiosity has declined in many countries, millennia of religious exposure have enforced the persistent idea that morality requires religious belief.

Will Gervais and colleagues tested the perception of a link between immorality and atheism in more than 3,000 people from 13 different countries on 5 continents, ranging from very religious societies (for example, United Arab Emirates and India) to very secular (for example, China and the Netherlands). To quantify prejudice against atheists, they provided participants with a description of an immoral person who initially tortures animals and eventually kills people for thrills. Half of the participants were then asked whether it was more probable that the perpetrator was: (1) a teacher; or (2) a teacher who is a religious believer. For the other half, option (2) was a teacher who does not believe in god(s). The authors then measured how frequently people chose option (2) over option (1) in each group.

The authors find that people are almost twice as likely to view extreme immorality as representative of atheists than of believers (except in Finland and, to a lesser extent, New Zealand), and that atheist participants also show the same prejudice against atheists. The study reveals that intuitive moral suspicion of atheists, although not universal, is culturally widespread, appearing in both secular and religious societies, and among both believers and atheists. It also reveals a significant divergence between scientific and lay perceptions of the relationship between religion and morality: although studies suggest that core moral instincts appear to emerge largely independent of religion, lay perceptions of a necessary link between morality and religion appear to be very strong.