"it doesn't have to be religion" Indeed, and Marxism (or its Communists avatars) fit the bill. However, none will deny it. None will tell that Marxism has nothing to do with Stalinism. Only Religions think they can claim that their ultra-fanatic followers are just wrong (well, they've got a point, but, you know, it is not a thing to do, even if they understand why, you'd know, offended they were... There are limits, you'd know, and they want to put them). And, in my knowledge, no one was killed because offending the feelings of Marx and his prophet Angels (joke). To joke about Stalin (or Mao) was probably deadly mind you.