The study bible says that Onesimus means “useful.” The whole situation of stealing and running away is useful in teaching about the love and forgiveness of Christ. Vs. 11 Formerly he was useless to you, but now he has become useful both to you and to me. Paul talks about how useless Onesimus was when he stole and ran away from Philemon. Nothing good can come out of the act of stealing itself. But when we see where this action took Onesimus, we see that the act of stealing led Onesimus to run away because of his guilt and shame, to where he literally ran to his salvation. This basically says that our feelings of condemnation and disgust about ourselves will lead us on the road to forgiveness when we repent and run to Jesus.
Think of how useless Onesimus must have felt. When I was living in sin, I defiantly felt useless and miserable. I think that is why it is called- the Good News! When someone is feeling so bad and useless, there is no better news, than the Good News! How can you transform a bad person into a good one? By sharing of our faith and hope in the Lord, and all of that is Good! Onesimus, who was once useless, has become very useful. When Onesimus was corrected and heard the Gospel, he recognized his sin and repented. He now has heard the Gospel and has the ability to share how Christ saved him.
Vs. 20 I do wish, brother, that I may have some benefit from you in the Lord; refresh my heart in Christ. Again, Paul emphasizes the goodness in Christ by sharing our faith. He is hoping that Philemon will take Onesimus back by humbling himself in the Lord. This will increase Paul’s faith in the Lord, when he sees Philemon forgive Onesimus. Actively sharing our faith means to forgive and love the people who have wronged us, and thus lead them to experience every good thing in Christ.