Catholics have a petty evil past as do other Christian religions, some pretty disturbing bits in the bible.
Those Muslims that follow the Koran word for word are few and far between, most Muslims don't take the Koran literally just as most Christians don't take the bible literally.
Dare say just as most Christians have not read much if any of the bible, there would be many Muslims who have not read the Koran.
Many of us identify as catholic, protestant, Anglican ect but don't actually follow the religion and/or go to church. Like wise many Muslims identify themselves as such but are not devoted followers, don't pray as required or attend mosques.
