Religious people are less intelligent than non-believers, according to a scientific review of a decades-long study.
A University of Rochester review of 63 studies found a "reliable negative relation between intelligence and religiosity" in 53 cases.
The studies include a life-long analysis of the beliefs of 1,500 gifted children with IQs over 135. which began in 1921 and continues today.
It found that even during early years, more intelligent children were more likely to turn away from religion.
In 1958, Michael Argyle wrote: "Although intelligent children grasp religious concepts earlier, they are also the first to doubt the truth of religion, and intelligent students are much less likely to accept orthodox beliefs, and rather less likely to have pro-religious attitudes."
Even in old age, the subjects of the study had far lower levels of belief in God than the average population.
The paper, which was published in the academic journal Personality and Social Psychology Review, concluded: "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'."
The author pre-empted efforts by secularists to highlight the findings by suggesting that highly intelligent people may be more likely to associate themselves with ideas around personal control and therefore less prone to accepting religious ideas.
"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."
They added: "People possessing the functions that religion provides are likely to adopt atheism, people lacking these very functions (e.g., the poor, the helpless) are likely to adopt theism."
The study comes as renowned atheist Richard Dawkins comes in for criticism even from fellow campaigners after he tweeted: "All the world's Muslims have fewer Nobel Prizes than Trinity College, Cambridge".