A recent review of studies found that religious belief is inversely associated with intelligence. That is, more intelligent people are generally less likely to be religious. The reasons for this are not fully understood, although some of the main theories were discussed in Tomas Chamorro-Premuzic’s article. Dr Chamorro-Premuzic also made the intriguing suggestion that the relationship between religiosity and intelligence might be mediated by the personality trait known as openness to experience. A related possibility is that greater knowledge about religion and the world in general might play some role in explaining why more intelligent people tend to be less religious.
To summarise briefly, a recent review of 63 studies showed that there is a moderate negative relationship between intelligence and religiosity (Zuckerman, Silberman, & Hall, 2013). The review found that religious beliefs, such as belief in God, are somewhat more strongly related to lower intelligence than religious behavior, such as church attendance. The authors estimated that the average difference in IQ points between believers and nonbelievers ranged from 6.2 for non-college samples to 7.8 for college samples. This difference is roughly half a standard deviation in size, so this represents a reasonably substantial effect rather than something trivial.
Studies like this are correlational in nature, so it is not possible to decide for sure what is causing the relationship. That is, we do not know whether intelligence causes people to be less religious, whether religion dampens a person’s intelligence, or whether there is some third variable underlying both. Dr Chamorro-Premuzic proposed that an underlying factor that might link intelligence and religiosity could be the personality trait openness to experience. This trait refers to the breadth and complexity of a person’s mental life. Openness to experience is positively correlated with general intelligence. Additionally, studies have found that non-religious people tend to be higher in openness to experience than the religious (Galen & Kloet, 2011), and that greater openness to experience is associated with more disbelief in God (Shenhav, Rand, & Greene, 2011). (I have written about this in a previous post here.)
Openness to experience, along with intelligence, is also associated with greater general knowledge of the world. This may be because people who are high in openness to experience are intellectually curious and therefore motivated to learn new things about the world. I think this is interesting because a Pew Forum survey on the religious knowledge of Americans found that atheists and agnostics had substantially more knowledge of religion than Christians on average. (A summary of the survey results can be viewed here, while the full report is here. You can take the quiz yourself here.)
In fact, atheists and agnostics scored higher on religious knowledge than any other group surveyed, including those who were “nothing in particular”, although Jews and Mormons also scored higher than the remaining groups interestingly enough. A breakdown of the results showed that Mormons had the most knowledge about Christianity, although atheists/agnostics and Jews knew more about Christianity than mainstream Christians on average. Atheists/agnostics, closely followed by Jews, had the most knowledge of world religions, such as Islam, Hinduism and Buddhism. Atheists/agnostics and Jews tend to be more educated than the other groups, and more education is associated with greater religious knowledge. However, even after taking education into account, atheists/agnostics and Jews still maintained their knowledge advantage over Christians generally. The Pew survey also included a short test of general knowledge for comparative purposes.
Atheists and agnostics also scored higher on this test than any other group, although Jews were again a close second, Mormons did somewhat less well, and other Christians were even further behind. Additionally, those who did well on the test of religious knowledge also tended to score well on general knowledge too, suggesting that those who know a lot about religion tend to be more knowledgeable in general.
The Pew survey report did not offer an explanation of why atheists/agnostics showed greater religious knowledge than most religious people. A number of possible explanations come to mind. As noted previously, people who are not religious tend to be more intelligent than the religious, and there is a positive association between intelligence and knowledge. An additional consideration is that atheists/agnostics, being higher in openness to experience, may have more interest in acquiring knowledge in general than the religious. This raises a question about the direction of causality. Does rejection of religion motivate people to gain more knowledge or does gaining knowledge lead to rejection of religion? Arguments can be made for each of these, although the actual answer might involve a combination of both, or even some third factor.
BY: Scott A. McGreal, MSc.