Make sure that nobody pays back wrong for wrong, but always strive to do what is good for each other and for everyone else.-1 Thessalonians 5:15
What is Paul talking about here? Paul is talking about vengeance and the idea that world has about vengeance. The world says that if you are wronged by someone that you well within your rights to attempt to pay that person back. In fact this concept is embedded in the Old Testament law when it says, “An eye for an eye, and a tooth for a tooth”. But when Jesus came along he turned everyone’s interpretation of this concept upside down. Here is what Jesus had to say about revenge.
You have heard that it was said, “Eye for eye, and tooth for tooth.” But I tell you do not resist an evil person. If anyone slaps you on the right cheek, turn them the other cheek also.-Matthew 5:38-39 NIV
What Jesus is basically telling us here is that you do not have the right to retaliate evil with evil. In fact he goes on to say this in the next section.
You have heard that was said, “Love your neighbor and hate your enemy.” But I tell you, love your enemies and pray for those who persecute you, that you may be children of your Father in heaven. He causes his sun to rise on the evil and the good, and sends rain on the righteous and the unrighteous. If you love those who love you, what reward will you get? Are not even the tax collectors doing that? And if you greet only your own people, what are you doing more than others? Do not even pagans do that? Be perfect, therefore, as your Heavenly Father is perfect.-Matthew 5:43-48 NIV
The key to not paying back wrong for wrong, is to love your enemies and to pray for those who have done you wrong.