In a recent Best Countries survey of more than 21,000 people from all regions of the world, the majority of respondents identified religion as the "primary source of most global conflict today."
Spiritual beliefs create an inherent "us vs. them" scenario, experts say.
"When societies shatter, they generally shatter along tribal lines. People are seeing themselves as irretrievably different from their neighbors," says Sam Harris, a neuroscientist and philosopher who has published books on Islam and the conflict between religion and science.

The divisions created by religion are deeper and potentially more harmful than those formed through other aspects of identity such as race, nationality or political affiliations because they confront individuals with differing opinions on the ultimate purpose of life, experts say. And more than 80 percent of those surveyed said that religious beliefs guide a person's behavior.

"Religion often becomes the master variable," Harris says. "It provides a unique reward structure. If you believe that the thoughts you harbor in this life and the doctrines you adhere to spell the difference between an eternity spent in fire or one spent on the right hand of God, that raises the stakes beyond any other reward structure on earth.