What does 1 Thessalonians 5:15 mean?

In this verse Paul appeals to his readers to do good to everyone, rather than trying to "get even" when someone commits an offense against them. Paul was a strong believer in the Lord's ability to address wrongdoing. In Romans 12:17–19 he writes, "Repay no one evil for evil, but give thought to do what is honorable in the sight of all. … Beloved, never avenge yourselves, but leave it to the wrath of God, for it is written, 'Vengeance is mine, I will repay, says the Lord.'" He adds in verse 21, "Do not be overcome by evil, but overcome evil with good."

Instead of looking for an opportunity to pay back offenders, we need to look for opportunities to forgive and bless them. Writing to the Colossian Christians, Paul instructed them to forgive "… each other; as the Lord has forgiven you, so you must also forgive" (Colossians 3:13). Although each of us had offended Jesus, He died for us, forgave us, and gave us everlasting life. Whenever we feel like taking revenge on someone, we ought to reflect on the grace and kindness Jesus showered on us in spite of the offenses we committed against Him.

It should be noted that Paul's instruction here does not merely say to be forgiving to brothers and sisters in Christ. While believers ought to be peaceful towards "one another," this verse specifically says this attitude ought to extend "to everyone."