Peter stresses that suffering persecution for the sake of Christ is not the same as suffering for crimes such as the sins listed in verse 15. Perhaps the civil authorities were telling the Christians that they should be ashamed of their behaviour because it was against the rules of the government or not conducive to a well-organised society. Or maybe some of their friends had become ashamed of Jesus and given up following him because of the persecution. Shame can be an appropriate response or it can be an expression of cowardice. It is appropriate when it is a response to personal sin. But shame is very inappropriate when it is a denial that we are followers of Jesus.
Of course, Peter himself knew what it was to be ashamed of knowing Jesus when he denied his Master three times in the house of Caiaphas, the Jewish high priest, on the night he was on trial. Peter did not intend to be ashamed, but he was ashamed because of his self-confidence. He had boasted that he would not deny Jesus, yet he did.
Instead of shame, the suffering Christian should live to glorify God. Note what Paul wrote in Philippians 1:19-21: ‘for I know that through your prayers and the help of the Spirit of Jesus Christ this will turn out for my deliverance, as it is my eager expectation and hope that I will not be at all ashamed, but that with full courage now as always Christ will be honoured in my body, whether by life or by death. For to me to live is Christ, and to die is gain.’ That was his attitude during his first Roman imprisonment.
He had a similar outlook during his second Roman imprisonment: ‘I was appointed a preacher and apostle and teacher, which is why I suffer as I do. But I am not ashamed, for I know whom I have believed, and I am convinced that he is able to guard until that Day what has been entrusted to me’ (2 Tim. 1:11-12).