The problem with religious belief is that (a) it is intellectually incoherent, and (b) real life provides plenty of evidence that invisible magical pixies don't exist. Thus the religionist suffers from cognitive dissonance and seeks to minimize this by forcing others to play the same game of make-believe.

Worse yet, because reality is complex and morality is always relative (see the trolley car problem for definitive proof of this) the simple-minded "rules for living" presented by religions always fail in real life, thus causing even more cognitive dissonance.

Once again, the "solution" is to rail at other people for having the temerity to fail to correspond to the simple beliefs presented by the religion in question.

Hence religion must always, inescapably, breed hatred and violence eventually.