You might think this could increase social tensions, but new research by Don Soo Chon, at Auburn University at Montgomery, Alabama, suggests that this may not be the case. He looked at how the level of ethnic, linguistic, and religious fragmentation relates to homicide rates in around 130 nations worldwide
He found that countries with a more diverse religious landscape did not, in fact have a higher homicide rate. However those with ethnic and linguistic divisions did.
He ran some simple models which adjusted for GDP and income inequality (low GDP and high inequality are both strongly linked to higher homicide rates), but this didn't change the basic findings.
So Chon's analysis suggests that ethnic and language barriers can increase murder rates, but religious differences do not. However, there are a few caveats.
The first is that we're looking at individual homicides here, not full-on wars or inter-communal violence. What's more, it could be argued that religious divisions exacerbate tensions mainly when they're aligned with ethnic and linguistic fault lines - they crystallise and fortify existing divisions.
It's also likely that countries with a diverse religious landscape actually have fewer religious tensions than countries that are dominated by two competing religions. As Chon says:
The probability of conflicts among different religious groups may be low when a democratic society guarantees free exercise of religion for all denominations, like in many Western countries. Instead, religious conflicts are likely to occur when two dominating religions in a country, such as Christianity and Islam, compete for dominance. However, the study does not test the competition between two dominating religious groups in a country.
And lastly, there's a fundamental problem with the data that Chon uses to measure religious diversity. It's the well-known (and widely used) 'fractionalization index' developed in 2003 by the Harvard economist Alberto Alesina, and one of the problems with it is that it takes no account of the fact that religions come in groups. So the different flavours of Protestantism are regarded as different religions in their own right - and just as different from each other as they are from, say, Hinduism and Islam.
So while this is study is a useful take on the problem which suggests that religion divisions don't increase social stress in the same way that ethnic and linguistic divisions do, there's still a lot more work needed to tease these issues out.
Chon, D. (2011). The Impact of Population Heterogeneity and Income Inequality on Homicide Rates: A Cross-National Assessment International Journal of Offender Therapy and Comparative Criminology DOI: 10.1177/0306624X11414813
This article by Tom Rees was first published on Epiphenom. It is licensed under Creative Commons.