One of the leading theories as to why people entertain religious belief is that it helps alleviate the fear of death. But a new systematic review of religious believers and non-believers that pulled data from a wide swath of high-quality international studies on the subject from 1961 to 2014 found that being religious doesn't always help relieve death anxiety after all. In fact, the research found that atheists were among the least fearful of death, reports Phys.org.

It's a study that calls into question the whole psychology of why religion is such a prominent and sustainable cultural artifact.

The studies that the review looked at were wide-ranging in their content. Some studies looked at specific types of religious beliefs, such as belief in God or gods, or belief in an afterlife. Other studies looked more closely at religious behavior, like going to church or praying. Different studies often made different distinctions. To identify consistencies across such diverse content, researchers checked for curvilinear patterns in the data.

This allowed them to narrow down their focus to just 11 key studies that were robust enough to make generalizations. Surprisingly, the researchers found that when data from these studies was graphed, 10 out of the 11 showed a distinct upside-down U shape, with religious believers and disbelievers showing less death anxiety than people in between. In other words, only people at the extremes — devout believers or atheists — received any kind of relief from death anxiety. The vast majority of religious believers tended to fear death more.

"It may be that other researchers would have found this inverse-U pattern too if they had looked for it. This definitely complicates the old view, that religious people are less afraid of death than nonreligious people," said Dr. Jonathan Jong, team leader on the review. "It may well be that atheism also provides comfort from death, or that people who are just not afraid of death aren't compelled to seek religion."

If religious belief is not alleviating the fear of death for the vast majority of religious followers — and if moderate religious belief may, in fact, be correlated with increased death anxiety — then it begs the question as to why such people are drawn to religion in the first place. It might be that alleviating the fear of death has little to do with it.

There are other theories about why people choose religious belief. For instance, some philosophers have posited that religion offers a grounding for one's moral inclinations. Meanwhile, others think in larger sociological terms, suggesting that religion gets reinforced because it performs certain organizing functions for a society. For instance, perhaps religious belief reinforces in-group, out-group psychology that acts as a cultural glue.

But if you're looking for coping mechanisms for death anxiety, it would seem that religion offers little reprieve unless you're fervently devout. And even in that case, extreme religiosity offers no discernible benefit over atheism or disbelief.

The review was published in the journal Religion, Brain & Behavior.