Nobody self-identifies more strongly as angels than those w…

Nobody self-identifies more strongly as angels than those who are possessed by demons.
The demons tell them that anything they do, no matter how evil, is in reality necessary and good. And how couldn't it be? They are the good, after all, which means everything they do is good.
A more complete inversion of ethics is hard to imagine:
Your actions are good, because you self-identify as good.
In ethics it's the other way around: you are good if your actions are good.