Do not be overcome by evil, but overcome evil with good.
-- Romans 12:21

A friend used to remind me that the number one goal in dealing with difficult people or circumstances is this: Don't become what you hate. He wasn't talking about hating the person, but despising their evil, wicked, petty, and sinful actions and motivations. We don't overcome the Devil by underhanded and dishonorable means. We overcome evil, we drive it back into the abyss, by doing what is right and filling our hearts and lives with goodness.