Quote:https://www.religjournal.com/pdf/ijrr10001.pdf

CONCLUSION: "There is sound evidence of a negative correlation between intelligence and religiosity and between intelligence and political extremism. This makes it unlikely that these results are a statistical fluke. Therefore the most probable reason behind elite social scientists being more religious than are elite physical scientists is that social scientists are less intelligent. Intelligence is also a factor in interdisciplinary differences in political extremism, physicists, who have high IQs, being among the least extreme and lower-IQ scholars being among the most extreme. Future research using larger academic samples would be extremely useful in exploring these areas in greater depth."

Studies comparing religious belief and IQ: According to biopsychologist Nigel Barber, the differences in national IQ are better explained by social, environmental, and wealth conditions than by levels of religiosity. He acknowledges that highly intelligent people have been both religious and nonreligious. He notes that countries with more wealth and better resources tend to have higher levels of non-theists and countries that have less wealth and resources tend to have fewer non-theists [perhaps due to religious beliefs generating hope, optimism, and group fellowship in harsh conditions, a role/purpose that is diminished in richer environments].

For instance, countries that have poverty, low urbanization, lower levels of education, less exposure to electronic media that increase intelligence, higher incidence of diseases that impair brain function, low birth weights, child malnutrition, and poor control of pollutants like lead have more factors that reduce brain and IQ development than do wealthier or more developed countries.