People who believe in God are less intelligent and don't use the analytical side of their brain as much, according to new research.
The study suggests religious people have fewer neurons sparking analytical thinking and have more empathy for other human beings.
Clashes between faith and scientific evidence to explain the world is perhaps most visible today in the arguments between evolution and creationism.
The conflict dates back centuries and could have its origins in the structure of our brains.
In a series of eight experiments, the researchers found the more empathetic the person, the more likely he or she is to be religious.
The finding offers a new explanation for past research showing women tend to hold more religious or spiritual world views than men.
The gap may be because women have a stronger tendency toward empathetic concern than men.
The study, published in the journal PLOS ONE, showed atheists are most closely aligned with psychopaths - not killers but those classified as such due to their lack of empathy for others.
To believe in a supernatural being or universal spirit people seem to suppress the brain network used for analytical thinking and engage the empathetic network, the scientists say.
When thinking analytically about the physical world people appear to do the opposite.
Professor Tony Jack, of Case Western Reserve University, said: "When there's a question of faith, from the analytic point of view, it may seem absurd.
"But, from what we understand about the brain, the leap of faith to belief in the supernatural amounts to pushing aside the critical/analytical way of thinking to help us achieve greater social and emotional insight."
A stream of research in cognitive psychology has shown and claims people who have are religious or spiritual are not as smart as others.
Prof Richard Boyatzis said: "They actually might claim they are less intelligent.
"Our studies confirmed that statistical relationship but at the same time showed people with faith are more pro-social and empathic."
The researchers examined the relationship between belief in God or a universal spirit with measures of analytic thinking and moral concern in a series of tests - each involving 159 to 527 adults.
Consistently through all eight the more religious the person the more moral concern they showed.
In earlier research Prof Jack 's lab used functional magnetic resonance imaging to show the brain has an analytical network of neurons that enables us to think critically and a social network that enables us to empathize.
When presented with a physics problem or ethical dilemma, a healthy brain fires up the appropriate network while suppressing the other.
Prof Jack said: "Because of the tension between networks pushing aside a naturalistic world view enables you to delve deeper into the social/emotional side.
"And that may be the key to why beliefs in the supernatural exist throughout the history of cultures. It appeals to an essentially non-material way of understanding the world and our place in it."
The study showed both spiritual belief and empathic concern were positively associated with frequency of prayer, meditations and other spiritual or religious practices.
Like other studies the experiments showed analytic thinking discourages acceptance of spiritual or religious beliefs.
Prof Boyatzis said: "Because the networks suppress each other they may create two extremes. Recognising this is how the brain operates, maybe we can create more reason and balance in the national conversations involving science and religion."
But the researchers say humans are built to engage and explore using both networks.
Baruch Aba Shalev's book 100 years of Nobel Prizes found from 1901 to 2000 almost 90 percent of Nobel laureates - or 654 - belonged to one of 28 religions.
The remaining 10.5 percent were atheists, agnostics or freethinkers.
Prof Jack added: "You can be religious and be a very good scientist."