With this phrase Peter is recalling the words he heard from Jesus in his Sermon on the Mount, “Blessed are those who are persecuted for righteousness’ sake, for theirs is the kingdom of heaven” (Matthew 5:10). We ought not to hear in the word “righteousness” in this verse the loading that Paul gives the term in, say, Romans 3:1 – 4:25 (where he uses it as a technical term to denote a right standing in the court of the heavenly Judge). Instead, Jesus’ work on the cross for sin leads to God’s people dying to sin and living a “righteous” life (1 Peter 2:24). So the term refers to a lifestyle that follows the example of Jesus Christ. In other words, it echoes Peter’s repeated references to doing good.
14 But even if you should suffer for righteousness’ sake, you will be blessed. Have no fear of them, nor be troubled,