The only reason anyone believes in any religion is they have been brainwashed.
That is why all religions major on getting the young indoctrinated from the earliest possible age.
I agree that it is inexplicable how millions of intelligent people around the globe all come to realise that they are Hindu / Muslim / Christian / Whatever FOR NO OTHER REASON than their parents were, and so forced them down the same path - yet remain convinced that the particular religion is the only true religion. Even though they can see that millions of others from other religions suffer from identical illusions.
Thousands of nutters across the ages have done - and continue to do - all manner of obscene acts citing their god in justification of them. If religion was abolished,nutters might still commit heinous crimes, but at least they wouldn't be able to make excuses and hide behind imaginary deities.