New research confirms that there is a negative relationship between religiosity and intelligence. The findings have been published in the scientific journal Personality and Social Psychology Bulletin.

“Religiosity is a pervasive phenomenon. Its influence can be felt in all spheres of life. However, a sizeable portion of the population defines itself as atheist. Why do some people decide not to be religious? I thought it was an important and fascinating question,” said study author Miron Zuckerman of the University of Rochester.

Zuckerman and his colleagues previously conducted a meta-analysis of 63 studies, which found “a reliable negative relation between intelligence and religiosity.” In other words, religious people tend to be less intelligent than non-religious people on average.

But that finding provoked a great deal of controversy. “Comments in the media ranged from expressions of surprise and curiosity to skepticism or even disdain about what intelligence tests actually measure,” the researchers wrote in their new study.

So Zuckerman and his colleagues decided to conduct another analysis with updated data. “Collecting new data to ascertain the validity of previous findings is crucial for science anytime, but especially when the subject matter is socially relevant and emotionally fraught,” they explained.

The new meta-analysis, which included data from 61 studies from the previous meta-analysis and new data from 22 studies conducted from 2012 to 2018, confirmed the previous findings. It also found no evidence that the negative relationship between religiosity and intelligence was growing weaker in recent years.

The results were based on data from more than 110,000 participants in total.

“The evidence that there is a negative relation between intelligence and religiosity is very strong. But the effect size of the relation is small. This means that there are factors besides intelligence that explain why people are or are not religious. It also means that although more intelligent people tend to be less religious on the average, predicting religiosity from intelligence for individuals is fallible,” Zuckerman told PsyPost.

The researchers also found evidence that cognitive styles explained some of the relationship between religiosity and intelligence. In particular, an analytic (as opposed to intuitive) thinking style was related to both increased intelligence and reduced religiosity.

“Although we present reasons for the negative relation, the empirical evidence for these explanation is not definitive,” Zuckerman said.

In addition, most of the studies were conducted in the United States. It is unclear if the findings apply to Eastern religions such as Buddhism and Hinduism.

“The negative relation was established for western societies. We don’t know whether it generalizes to other populations, particularly those in the Far East,” Zuckerman explained.

The study, “The Negative Intelligence–Religiosity Relation: New and Confirming Evidence“, was authored by Miron Zuckerman, Chen Li, Shengxin Lin, and Judith A. Hall.