Christians nowadays have been exposed to so much news about how religion is causing division in today's world. The seemingly endless atrocities being committed by the terrorist group Islamic State (ISIS), for instance, have triggered much debate as to how other Christians and other religious groups should treat Muslims.

This social tension caused by religion, however, is not a product of the modern world, according to a new study published on the journal "Current Anthropology." In fact, researchers have concluded that religion has been causing conflict for over 2,000 years now.

Anthropology professor Arthur Joyce from the University of Colorado and associate professor Sarah Barber from the University of Central Florida arrived at this conclusion after studying several archaeological sites in Mexico, in the lower Río Verde Valley of Oaxaca, located in the country's Pacific coastal lowlands.

Barber said the evidence they gathered seemed to run counter to the long-held belief that religion united early civilisations.

"It doesn't matter if we today don't share particular religious beliefs, when people in the past acted on their beliefs, those actions could have real, material consequences," Barber said in an article posted on the University of Colorado's website.

"It really behooves us to acknowledge religion when considering political processes," she added.

The researchers particularly found out based on archaeological evidence from 700 B.C. to A.D. 250 that civilisations in the site of the study failed to create state institutions because of strong religious ties in smaller communities.

Contrast this to the highland Valley of Oaxaca, where a regional state emerged at the hilltop city of Monte Alban primarily due to some elite's mediation between their communities and the gods. Even this, however, triggered conflict among traditional community leaders.

"In both the Valley of Oaxaca and the Lower Río Verde Valley, religion was important in the formation and history of early cities and states, but in vastly different ways," Professor Joyce, the study's lead author, meanwhile said.

"Given the role of religion in social life and politics today, that shouldn't be too surprising," he added.