2) An Ends -Justifies-the-Means Mentality.
Utopianism and a willingness to use any means to achieve a predetermined “good” end can devastate the lives of other human beings — and even that assumes the “good” outcome is really good. Jim Jones, Pol Pot, and the KKK all probably believed what they were doing was right and good. Yet in the end they turned out to be doing evil in pursuit of an evil end. This is the norm of human history since the beginning of time.
Of course, theoretically, one might create a good outcome by using evil means, but it’s very difficult in the real world because evil tends to spawn more evil and provoke retribution. Tactics adopted by one side inspire the other. Crossing one moral line usually leads to crossing another and taking things to further extremes. Some of the worst devils you’ll ever run across are people who believe themselves to be working for the best ends.