But I tell you, do not resist an evil person. If anyone slaps you on the right cheek, turn to them the other cheek also.
The LORD clearly wants us to not respond to evil with evil, but to respond with humility and love. David illustrates this ideal very well in 2 Samuel 16:5-14. In this part of the story David and his army get cursed and abused by an enemy of theirs. One of David's men desperately wants to kill the man, but David stops him, saying:
"Leave him alone; let him curse, for the Lord has told him to."
2 Samuel 16:11b
David told his men to respond PEACEFULLY. He had them keep walking even though their every instinct told them to attack. David did something that is hard for most-- he met evil with good.
No matter what evil you may face, don't succumb to the urge to fight back! Instead show grace and humility and meet their violence with love. When you meet evil with more evil, the evil has won and you have accomplished nothing but made the fire bigger.
So, as Romans 12:21 says, over come the evil with GOOD! Be a light in this world of darkness and meet every bad thing with a positive response.