The book of Philemon was a personal letter to Philemon, a rich leading member of the church at Colossae. It is thought that Philemon was a slave owner or at least had servants at the time he accepted Christ and became a faithful Christian. One of his slaves/servants was named Onesimus (meaning “useful”). Before accepting Christ, Onesimus ran away from his master and went to Rome. While in Rome, he came in contact with the Apostle Paul. He had probably met Paul previously while Paul was visiting in the home of his master, Philemon. Through Paul’s ministry, Onesimus accepted Christ and became a devoted servant of the Lord. He realized that he had disobeyed the laws of the time in running away from his master, and that now, as a Christian, his course of duty was to return and seek the forgiveness of Philemon. 

This situation presented a difficult problem for both Onesimus and Philemon. If Onesimus was a slave not a servant, Paul would have been in trouble for not returning him or having him returned to Philemon, so it is thought that Onesimus was actually a servant of Philemon. Paul would like to have Onesimus stay and minister to him, but he realized that that would not be right without Philemon’s blessing, and it would be contrary to Onesimus’ wanting to return to Philemon. Paul wrote a letter to Philemon for the former servant to deliver to his master personally when he returned to him. In this letter, he tells Philemon how close he has gotten to Onesimus and asks Philemon to take back his former servant and to treat him now as a brother in Christ (v. 16-17).

When the Jews rejected Jesus as their Messiah, his teachings then went out to the Gentiles. Both bond and free man were “called” to follow in the footsteps of Jesus. Paul even admonishes the converted slaves to be obedient to their Christian masters, and the masters to love their slaves (Ephesians 6:5-9, Colossians 3:22-25; 4:1).

Paul writing the letter to Philemon on Onesimus’ behalf could be a picture of the mediation and intercession of Christ for us poor sinners. Jesus Christ finds us and works a change in us, and then intercedes for us with the Father that we may be received into his favor and family, with past offenses forgiven.

Since the “little flock” class, to whom it is the Father’s good pleasure to give the kingdom, are being prepared to administer the laws of God for the blessing of all mankind, it is important they become developed in love, that all selfishness be put away; for only then will they become properly qualified to participate in the rulership of that new kingdom which has had its great objective the establishment of the will of God in earth as it is in heaven.

(Various translations seem to put emphasis in different places in the epistle, therefore it is difficult to pick one verse that seems to be the most important, except for the concepts described above regarding v. 16-17.)

Additional Resource: 
Christian Questions Podcast 
Episode #1166: “How Did the Apostle Paul Handle a Slave Owner?” 
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