A religious leader tells his followers to invade and steal the land of followers of a rival. What will happen to the inhabitants? No problem: they are to be slaughtered, every last man, woman and child. Even their animals. And their city burned and every vestige of them destroyed (apart from silver, gold and other valuables which they keep for the Leader).
On other occasions the Leader:
This all happened a long time ago, but even in recent times followers of this bloodthirsty character continue to wage horrific wars in the name of their Leader. These are mostly directed at each other: they have by now split into 3 main factions, each of which has itself split into many sub-factions, all of whom regard each other with various degrees of enmity. Other acts of violence perpetrated by the Leader's followers, many of them in his name, include systematic mass-exterminations, destruction of buildings, aeroplanes, trains and buses full of people, and random bombings too numerous to mention, mostly directed at civilians.
And this Leader is supposed to be the Good guy!
There's a bad guy who's supposed to be as bad as bad can be; but doesn't seem to actually do anything (although various disasters - man-made as well as natural - are blamed on him by followers of the "good" guy). His followers seem to be mainly poseurs: if they ever get to do any actual bad stuff it's utterly dwarfed by the other lot's activities.
Who would I choose, if I had to? I'm fortunate to have the choice (to choose neither, in my case). But for most of the last few thousand years - and still today in many parts of the world - I could be punished, even killed, for not following whichever particular faction of the Leader currently held power in that part of the world.