Research indicates that Philemon was a very influential Christian in the area of Colossae and Laodicea with his house being a meeting place for the church. He was a close friend of Paul and was probably converted during his ministry at Ephesus.
Onesimus, one of Philemon’s slaves had run away and eventually arrived in Rome where he met Paul and was converted to Christ. Slaves were chattel property and had no civil rights, but had an obligation to faithfully serve their masters. Christianity did not abolish slavery, but it recognized Christian slaves and masters as brothers.
After his conversion, Onesimus had become a friend and helper of Paul. Even though he was of great assistance, Paul persuaded him to return to his master, Philemon.
Paul wrote the letter to Philemon to inform him of the conversion of Onesimus and to ask that he receive him back as a brother in Christ. This letter was probably written during his imprisonment in Rome about A.D. 62 at the same time Ephesians and Colossians were written and was carried by Onesimus as he returned to his master.
In his letters to the various churches, Paul felt that it was needful to begin by reminding them of his authority as an apostle. It was not necessary to repeat that to Philemon because of their close friendship. He did, however, state that he was a prisoner of Christ Jesus. Timothy who probably did the writing for him was present.
It is thought that Apphia was Philemon’s wife and that Archippus was his son. He also addressed the church in Philemon’s house as they also were interested in the welfare of Onesimus.