A review of scientific studies finds that people who hold a more naturalistic view of the world are generally smarter than those who believe in god.

In an analysis of 63 studies conducted since 1928, a researcher at the University of Rochester found “a reliable negative relation between intelligence and religiosity” in 53 of the studies. While 10 of the studies showed a positive correlation, only two of them showed a significant link.

Thirty-five of the studies, however, showed a significantly negative correlation between intelligence and religiosity, according to researcher Miron Zuckerman.

"Most extant explanations [of a negative relation] share one central theme —the premise that religious beliefs are irrational, not anchored in science, not testable and, therefore, unappealing to intelligent people who 'know better,’” Zuckerman wrote in a paper published this month.

Zuckerman and two other psychologists reviewing the literature defined intelligence as the “ability to reason, plan, solve problems, think abstractly, comprehend complex ideas, learn quickly, and learn experience.” Religiosity is defined by psychologists as participation in some facets of worship, which might range from passive attendance at weekly services to the sort of messianic fervor depicted in Robert Duvall’s 1997 film The Apostle.

Other factors such as sex or education made no difference in the correlation between intelligence and religiosity, although some variance was seen with age. The association of lower intelligence with religiousness was weakest among teenagers in the “pre-college population,” however.

Yet, a lifelong association between higher intelligence and atheism, or naturalistic worldview, remains constant in a continuing study — begun in 1928 — of 1,500 gifted children with intelligence quotients (IQs) over 135. Even in extreme old age and closer to death (and some would say God), these children remained steady in their beliefs, or non-belief.

The higher intelligence of non-believers was attributed by researchers to a greater propensity to seek education and higher employment, when available, thus assuming more personal control over their direction in life. "Intelligent people typically spend more time in school — a form of self-regulation that may yield long-term benefits," Zuckerman wrote. "More intelligent people get higher level jobs and better employment may lead to higher self-esteem, and encourage personal control beliefs."

Defenders of religious belief contend the psychologists define intelligence too narrowly as analytical ability, omitting such aptitudes as emotional and creative intelligence among other aspects of multiple intelligence theory — and certainly wisdom remains an ineffable quality, slipping just out of grasp.

Although many evangelical Americans might be surprised to learn of a more deist tradition among the Founding Fathers, the nation’s religious may cite at least one notable exception to the study’s conclusion: Albert Einstein.

Source: Zuckerman M. The Relationship Between Intelligence And Religiosity: A Meta-Analysis And Some Proposed Explanations. Personality And Social Psychology Review. 2013.