The simple fact is, some people like to hurt and kill other people. At one end of the scale they are simply nasty horrible self-hating wonks, and at the other end, they are psychopaths who are unable to feel any sympathy for, and empathy with their victims.
Now some people simple go about their ghastly business on their own, ploughing a lone furrow, and getting on with what they do until they are caught, or they die, whichever comes first.
But some have the herd mentality, they want to be in a gang, so they hang their dreadful behaviour on a religion of one sort or another, and find relevant tracts in its writings that can be shoehorned into something that they believe supports their actions.
So removing said tracts won't stop this behaviour, it is inbuilt, and the religious aspect is simply a prop, a crutch, something to lean on to make themselves feel justified in their towering self-righteousness, they can quote buts to each other to underline their self-belief in what they are doing.
Not everyone needs an excuse to be horribly violent to complete strangers, but for those who do, a quick scan of the 'holy book' will help them get a night's sleep, or give them a sense of belonging when they all shout out bits in unison.
Removing religious doctrine, in an ideal world, would cancel out the support for a proportion of deeply disturbed individuals, but it would never ever stop all of them.