operating under the belief that they are saving the world
That's the most dangerous of evil. Not evil for evil's sake, but instead doing what they view as right.
In literature, they also make for the most dangerous villains.
Zealotry is scary in any form. Religious, political, scientific, dietary, legal... Doesn't matter. When a person doesn't leave room for reason, critical thinking, and compassion, they can do some very despicable things.
That's the most dangerous of evil. Not evil for evil's sake, but instead doing what they view as right.
In literature, they also make for the most dangerous villains.
Zealotry is scary in any form. Religious, political, scientific, dietary, legal... Doesn't matter. When a person doesn't leave room for reason, critical thinking, and compassion, they can do some very despicable things.