8 Therefore, although in Christ I could be bold and order you to do what you ought to do, 9 yet I prefer to appeal to you on the basis of love. It is as none other than Paul—an old man and now also a prisoner of Christ Jesus — 10 that I appeal to you for my son Onesimus, who became my son while I was in chains. 11 Formerly he was useless to you, but now he has become useful both to you and to me. Philemon 8-11
People mature with age, usually. Onesimus was one of those people. I’m not sure what Onesimus did to warrant a negative reputation with Philemon but there seemed to be a correlation between helping Paul while he was in prison and being considered useful again. Paul, like he did quite often, gave people a second chance if he saw promise.
We’ve also been given plenty of second chances in life. Christ obviously gave us a second and third and umpteenth chance. Without Him we’d be hopelessly lost.
Praise the Lord for second and third and fourth chances. Praise Him for his infinite mercy and grace.