Nyborg also co-authored a study with Richard Lynn, emeritus professor of psychology at the University of Ulster, which compared religious belief and average national IQs in 137 countries. The study analysed the issue from several viewpoints. Firstly, using data from a U.S. study of 6,825 adolescents, the authors found that atheists scored 6 IQ points higher than non atheists.
Secondly, the authors investigated the link between religiosity and intelligence on a country level. Among the sample of 137 countries, only 23 (17%) had more than 20% of atheists, which constituted “virtually all... higher IQ countries.” The authors reported a correlation of 0.60 between atheism rates and level of intelligence, which was determined to be “highly statistically significant”.
Professor Gordon Lynch, director of the Centre for Religion and Contemporary Society from London's Birkbeck College, expressed concern that the study failed to take into account a complex range of social, economic and historical factors, each of which has been shown to interact with religion and IQ in different ways. Gallup surveys, for example, have found that the world's poorest countries are consistently the most religious, perhaps because religion plays a more functional role (helping people cope) in poorer nations.
Commenting on some of the above studies in The Daily Telegraph, Lynn 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. Several Gallup poll studies of the general population have shown that those with higher IQs tend not to believe in God." A study published in Social Psychology Quarterly in March 2010 also stated that "atheism ...correlate[s] with higher intelligence".
...belief in God may be intuitive for reasons related to more general features of human cognition that give rise to tendencies toward dualism (Bering, 2006, 2011), anthropomorphism (Epley,Waytz, & Cacioppo, 2007; Waytz et al., 2010), and promiscuous teleology (Kelemen & Rosset, 2009)... What’s more, the belief in God may give rise to a feedback cycle whereby satisfying explanatory appeals to God reinforce the intuitive cognitive style that originally favored the belief in God.
- Amitai Shenhav, David G. Rand, and Joshua D. Greene
Even at the scale of the individual, IQ may not directly cause more disbelief in God. Dr David Hardman of London Metropolitan University says: "It is very difficult to conduct true experiments that would explicate a causal relationship between IQ and religious belief." He adds that other studies do nevertheless correlate IQ with being willing or able to question beliefs.
Researcher Gregory S. Paul's findings suggest that economic development has a closer relationship with religiosity. He argues that once any "nation's population becomes prosperous and secure, for example through economic security and universal health care, much of the population loses interest in seeking the aid and protection of supernatural entities." Other studies have shown that increased wealth is correlated with a decline in religious beliefs. Indeed, the majority of the nations that showed a strong relationship between low religiosity and high IQ in the 2008 study were developed nations.