Moreover, the chief complaint against religion -- that it is history's prime instigator of intergroup conflict -- does not withstand scrutiny. Religious issues motivate only a small minority of recorded wars. The Encyclopedia of Wars surveyed 1,763 violent conflicts across history; only 123 (7 percent) were religious. A BBC-sponsored "God and War" audit, which evaluated major conflicts over 3,500 years and rated them on a 0-to-5 scale for religious motivation (Punic Wars = 0, Crusades = 5), found that more than 60 percent had no religious motivation. Less than 7 percent earned a rating greater than 3. There was little religious motivation for the internecine Russian and Chinese conflicts or the world wars responsible for history's most lethal century of international bloodshed.
Indeed, inclusive concepts such as "humanity" arguably emerged with the rise of universal religions. Sociologist Rodney Stark reveals that early Christianity became the Roman Empire's majority religion not through conquest, but through a social process grounded in trust. Repeated acts of altruism, such as caring for non-Christians during epidemics, facilitated the expansion of social networks that were invested in the religion. Likewise, studies by behavioral economist Joseph Henrich and colleagues on contemporary foragers, farmers, and herders show that professing a world religion is correlated with greater fairness toward passing strangers. This research helps explain what's going on in sub-Saharan Africa, where Islam is spreading rapidly. In Rwanda, for example, people began converting to Islam in droves after Muslims systematically risked their lives to protect Christians and animists from genocide when few others cared.
Although surprisingly few wars are started by religions, once they start, religion -- and the values it imposes -- can play a critical role. When competing interests are framed in terms of religious and sacred values, conflict may persist for decades, even centuries. Disputes over otherwise mundane phenomena then become existential struggles, as when land becomes "Holy Land." Secular issues become sacralized and nonnegotiable, regardless of material rewards or punishments. In a multiyear study, our research group found that Palestinian adolescents who perceived strong threats to their communities and were highly involved in religious ritual were most likely to see political issues, like the right of refugees to return to homes in Israel, as absolute moral imperatives. These individuals were thus opposed to compromise, regardless of the costs. It turns out there may be a neurological component to such behavior: Our work with Gregory Berns and his neuroeconomics team suggests that such values are processed in the brain as duties rather than utilitarian calculations; neuroimaging reveals that violations of sacred values trigger emotional responses consistent with sentiments of moral outrage.