A new review of 63 scientific studies stretching back over decades has concluded that religious people are less intelligent than non-believers.
A piece of University of Rochester analysis, led by Professor Miron Zuckerman, found “a reliable negative relation between intelligence and religiosity” in 53 out of 63 studies.
According to the study entitled, 'The Relation Between Intelligence and Religiosity: A Meta-Analysis and Some Proposed Explanations', published in the 'Personality and Social Psychology Review', even during early years the more intelligent a child is the more likely it would be to turn away from religion.
In old age above average intelligence people are less likely to believe, the researchers also found.
One of the studies used in Zuckerman's paper was a life-long analysis of the beliefs of 1,500 gifted children with with IQs over 135.
The study began in 1921 and continues today. Even in extreme old age the subjects had much lower levels of religious belief than the average population.
The review, which is the first systematic meta-analysis of the 63 studies conducted in between 1928 and 2012, showed that of the 63 studies, 53 showed a negative correlation between intelligence and religiosity, while 10 showed a positive one.
Only two studies showed significant positive correlations and significant negative correlations were seen in a total of 35 studies.
The authors of the review looked at each study independently, taking into account the quality of data collection, the size of the sample and the analysis methods used.
The three psychologists carrying out the review defined intelligence as the “ability to reason, plan, solve problems, think abstractly, comprehend complex ideas, learn quickly, and learn from experience”.
Religiosity is defined by the psychologists as involvement in some (or all) facets of religion.
According to the review, other factors - such as gender or education - did not make any difference to the correlation between intelligence and religious belief.
The level of belief, or otherwise, did however vary dependent upon age with the correlation found to be weakest among the pre-college population.
The paper concludes that: "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'."
Criticisms of the conclusions include that the paper only deals with a definition of analytic intelligence and fails to consider newly identified forms of creative and emotional intelligence.
The psychologists who carried out the review also sought to pre-empt the secularist interpretation of the findings by suggesting that more intelligent people are less likely to have religious beliefs as they associate themselves with ideas around personal control.
"Intelligent people typically spend more time in school - a form of self-regulation that may yield long-term benefits," the researchers wrote.
"More intelligent people get higher level jobs (and better employment (and higher salary) may lead to higher self-esteem, and encourage personal control beliefs."