Belief that your way is the right way, can be described as self-centred or egocentric.
This question was asked in the context of religion, so it is appropriate to review this meaning in the context...
If you mean how do humans hurt their bodies this is how they do it:Fail to eat or drink waterOvereat, binge and vomit.Use dangerous drugs, illegal drugs and overdose legal drugs.Drink too much...
Firearms, medieval weaponry, rape whistle, pepper spray, mad karate skills, indestructible bubble suit, shoot any one that comes within 5 miles of you, or have Chuck Norris on speed dial.