Religious people are less intelligent on average than atheists because faith is an instinct and clever people are better at rising above their instincts, researchers have claimed.

The theory — called the 'Intelligence-Mismatch Association Model' — was proposed by a pair of authors who set out to explain why numerous studies over past decades have found religious people to have lower average intelligence than people who do not believe in a god.

A 2013 analysis by University of Rochester found “a reliable negative relation between intelligence and religiosity” in 53 out of 63 historic studies.

A negative correlation between intelligence and religion makes sense if religion is considered an instinct, and intelligence the ability to rise above one's instincts, say researchers Edward Dutton and Dimitri van der Linden in their new paper published today.

Writing for Springer’s journal of Evolutionary Psychological Science, the authors – who are based at the Ulster Institute for Social Research and Rotterdam University respectively – explained their model is based on the ideas of evolutionary psychologist Satoshi Kanazawa.

Mr Kanazawa's 'Savanna-IQ Principles' suggest human behaviour will always be guided by the environment in which their ancestors developed.

Mr Dutton and Mr van der Linden argue in keeping with this that religion should be considered an 'evolved domain' — or instinct.

Rising above instincts is advantageous, they said in a statement, because it helps people to solve problems.

“If religion is an evolved domain then it is an instinct, and intelligence — in rationally solving problems — can be understood as involving overcoming instinct and being intellectually curious and thus open to non-instinctive possibilities,” explained Mr Dutton.

According to the 2013 review, the more intelligent a child is — even during early years — the more likely it is to turn away from religion.

In old age, above-average-intelligence people are less likely to believe in a god.

Mr Dutton and Mr van der Linden also investigated the link between instinct and stress, and the instinctiveness with which people tend to operate during stressful periods.

They argue that being intelligent helps people during stressful times to weigh up their options and act rationally rather than give in to knee-jerk responses.

“If religion is indeed an evolved domain — an instinct — then it will become heightened at times of stress, when people are inclined to act instinctively, and there is clear evidence for this,” said Mr Dutton.

“It also means that intelligence allows us to able to pause and reason through the situation and the possible consequences of our actions.”

The researchers believe that people who are attracted to the non-instinctive are potentially better problem solvers.

“This is important, because in a changing ecology, the ability to solve problems will become associated with rising above our instincts, rendering us attracted to evolutionary mismatches,” said Mr van der Linden