9b I then, as Paul–an old man and now also a prisoner of Jesus Christ–10 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. 12 I am sending him–who is my very heart–back to you.
13 I would have liked to keep him with me so that he could take your place in helping me while I am in chains for the gospel. 14 But I did not want to do anything without your consent, so that any favor you do would not seem forced but would be voluntary. 15 Perhaps the reason he was separated from you for a little while was that you might have him back forever– 16 no longer as a slave, but better than a slave, as a dear brother. He is very dear to me but even dearer to you, both as a fellow man and as a brother in the Lord.
Paul writes this short letter while imprisoned in Rome for speaking the gospel (thus the phrase “prisoner of Jesus Christ”). He sends it to Philemon, a slave owner and Christian believer living in Colosse. The man Onesimus, whom Paul speaks so highly of here, was once one of Philemon’s slaves; Onesimus was stolen from Philemon, but he had also run away once, meriting the punishment of death under Roman law.
The reason Paul speaks so strongly for Philemon to accept Onesimus again is because Onesimus has become a Christian in the interim, and has helped Paul quite a bit in spreading the gospel. Paul had, indeed, found him to be very useful (which is what “Onesimus” means), and had thought about keeping the man along with him on his missions. But Paul also knew that the legal and emotional rift between Philemon and Onesimus needed to be brought to conclusion and healed. So he sends this persuasive letter to Philemon, asking him to consider Onesimus now “no longer as a slave, but…as a dear brother” in Christ, a fellow believer who could now help Philemon with the gospel message as well. (In verse 18, not quoted here, Paul also offers to pay off any remaining debts or wrongdoings on Onesimus’ record, to further clear his name.)
In doing this, Paul is not only freeing Onesimus from indebtedness to his former master; he is modeling on a much smaller scale what Christ did for us. Onesimus was freed from the punishment that awaited him–a death sentence–and instead was granted life with fellow believers…just as we believers were freed from sin’s wages of death and granted eternal life with God. Of course, Paul was not crucified for Onesimus as Jesus was for us, but the main idea remains the same: redemption can belong to each of us, no matter how deep in sin we are, because Jesus has settled our sin debt and freed us all.