Compassion Against Evil
Compassion is not an emotion. It is a deliberate choice. It is not antithetical to fear, anger, or even hatred. Compassion is using empathy and self-awareness to say, I'm feeling these strong emotions. They are valid feelings and I understand them. But I'm not going to let them control me, I'm not going to give in to letting them hurt people, even bad people. Even evil people.
I can despise their actions. I can feel righteous fury at their beliefs. I can take actions, even severe if needed, to prevent them from harming others. But can still see the other person as the human they are. They've felt the same emotions as me: sadness, fear, heartbreak. I can relate to that suffering, and it reminds me that they are not monsters. They are humans. They are the worst of us, the violent, the reprehensible, the pure malevolence against their fellow humans.
We call them "monsters" because we don't want to even see them as people, but they are. We cannot deny that they are the worst manifestation of humanity; they are the worst that we are capable of. And yet they are still one of us. Compassion shown toward these individuals, it's seen as condoning them. Or even so far as to say compassion is immoral in these instances.
We want to be angry. It feels so good to insult, to belittle, to condemn, especially when we feel it's justified. That you are morally right to damage them, as they have damaged others, which makes it that much harder to not let the hatred drive you. It's difficult to be compassionate; you feel they are "getting away with it", or even that your harmful actions are you carrying out some kind of karmic justice.
We want to be compassionate, but sometimes our instinctual lashing out feels too good to pass up. Hatred comes naturally. Compassion must be tended, practiced, and grown. Our legacy as a generation, as a society, and as a species cannot help but be tainted by evil, but that evil does not have to define us. Instead, what a proud legacy we can leave, being defined by compassion.