after further thought -
the results of that study seem to be one specific example of a more generalized truth about people: that many will commit violence if told to by ANY external authority which they accept and trust.
Ever hear of Stanley Milgram?
I set up a simple experiment at Yale University to test how much pain an ordinary citizen would inflict on another person simply because he was ordered to by an experimental scientist. Stark authority was pitted against the subjects' [participants'] strongest moral imperatives against hurting others, and, with the subjects' [participants'] ears ringing with the screams of the victims, authority won more often than not. The extreme willingness of adults to go to almost any lengths on the command of an authority constitutes the chief finding of the study and the fact most urgently demanding explanation.
So, it ain't purely about religion. OTOH one could justifiably argue that religion encourages this syndrome by setting up an external authority which one should trust and obey. That might be true, but I still say: remove religion and you won't stop the problem.
Even anarchists, who reject all external authority in favor of collective agreement and cooperation, have been known to commit violence, to put it mildly ..