Because it implies people are aware they are committing evil yet they sure don't behave like they did, and some may not agree that they committed evil. It implies the world is as morally black and white as it is in the Bible and most works of fiction, when it clearly isn't.
Would it be considered "evil" for an LGBT militia group to execute an evangelical Christian church pastor linked to dozens of anti-LGBT crimes and murders? You might think so, but for many others, he/she deserved it for what they did.