The system in which a person is enmeshed can inspire evil.
This guy studied the Milgram Electro-learning experiments. He worked on the Stanford Prison Study. He has created evil in a jar. I suspect that most people think that evil can’t infect them, but Zimbardo proved that it can. He spells out how it is that Abu Ghraib can happen.
Here is the recipe for evil: Give people a goal, add authority, defer responsibility, remove dissenters, and you can create hell.