My take:

Sinners = all of us. We know what's right and we know what's wrong, and in a moment of weakness, pride, jealousy, anger, etc, we do the wrong thing. Eventually (minutes, hours, days...) we realize we screwed up, we feel remorse, we apologize, we seek forgiveness, we move on, learn from our mistakes and we try to become better more sinless people.

Evil = those who have no concept or care about what's right or wrong. They act impulsively without any remorse or thought regarding the consequences of their actions.

I imagine that people like Jefferey Dahmer experience no more feelings as teenagers when they torture and kill animals than we do when we cut the lawn. They might understand that some authority figure will become upset about their actions for "some reason" but they don't feel badly about anything they do.