A new study just published in the journal PLoS One by University of Oregon psychologist Azim F. Shariff and University of Kansas statistician Mijke Rhemtulla looks at the "Divergent Effects of Beliefs in Heaven and Hell on National Crime Rates." They find that the fear of God works much better at keeping people on the straight-and-narrow than does belief in divine mercy. Laboratory studies had earlier found that having Christian undergraduates spend ten minutes writing either on God's forgiving nature or His retribution for sins primed them for a subsequent task in which they could cheat. The students who wrote about divine retribution cheated considerablly less than those who focused on divine foregiveness. As the researchers explain:
This pattern of results is consistent with theories highlighting the effectiveness of supernatural punishment–specifically–at regulating moral behavior and, as a result, group cooperation. These theories argue that human punishment is a highly effective deterrent to anti-social behavior within groups, but one that faces inevitable limitations of scale. Human monitors cannot see all transgressions, human judgers cannot adjudicate with perfect precision, and human punishers are neither able to apprehend every transgressor, nor escape the potential dangers of retribution. Divine punishment, on the other hand, has emerged as a cultural tool to overcome a number of those limitations. Unlike humans, divine punishers can be omniscient, omnipotent, infallible, and untouchable-and therefore able to effectively deter transgressors who may for whatever reason be undeterred by earthly policing systems.
Supernatural benevolence, however, is not theorized to be similarly effective at stabilizing cooperation within groups. Moreover, the evidence thus far suggests that though the more ‘positive’ religious attributes may provide their own benefits, such as better self-esteem or health coping, their role in encouraging moral behavior may be, at best, minimal and, at worst, negative.
Using these theoretical insights, the two researchers gathered up statistics on national rates of belief in Heaven and Hell and their national crime rates to see how (if) they correlated. They also took into account income inequality, GDP per capita, life expectancy, degree of urbanization, and so forth. Their analysis concludes:
The present analysis has uncovered two strong, unique, and reliable relations between religious belief and national crime rates. The degree to which a country’s rate of belief in heaven outstrips its rate of belief in hell significantly predicts higher national crime rates. Statistically, this finding manifests in two independent effects: the strong negative effect of rates of belief in hell on crime, and the strong positive effect of rates of belief in heaven on crime....
...these findings coalesce with theoretical and empirical work suggesting that beliefs in punishing and omniscient supernatural agents spread across historical societies primarily because of their ability to foster cooperation and suppress anti-social behavior among anonymous strangers.
If believers actually are primarily motivated to moral behavior by fear of damnation, it's no wonder that they don't much like or trust atheists.