I should also like to point out that any correlations between religion and atrocities or no-religion and atrocities doesn't imply a causal relationship between religious stance and propensity to commit atrocities. Hence the Crusaders, the Inquisition or Al Quaeda probably didn't commit atrocities primarily because they were religious but because they were interested in acquiring (earthly) political power and justified their actions on religious grounds. Hitler and Stalin, on the other hand, were atheists (i.e. couldn't give a toss about religion) and justified their actions on political grounds.