"Any of us would be shocked if someone we knew and admired killed children. But these days it’s especially hard to think through these situations because of the worldview that prevails in our culture.
According to this view, most people are naturally good, because nature is good. The monstrosities of the world are caused by the few people (like Hitler or Idi Amin) who are fundamentally warped and evil.
This worldview gives us an easy conscience, because we don’t have to contemplate the evil in ourselves. But when somebody who seems mostly good does something completely awful, we’re rendered mute or confused.
But of course it happens all the time. That’s because even people who contain reservoirs of compassion and neighborliness also possess a latent potential to commit murder."