Once there was a man named Philemon, apparently a reasonably wealthy man, as he owned at least one slave, whose name was Onesimus. It is noteworthy that Onesimus means "useful", because the one so named proved otherwise: he ran away. Philemon was a Christian, converted through Paul's ministry, and I don't expect that he treated Onesimus particularly badly, as slave treatment in the Roman Empire went; but there is nothing particularly pleasant about being a slave at all, and this one had had enough. If we are correct in identifying this slave with the Onesimus mentioned in Colossians 4:9, then it is reasonable to assume that all this took place in or near Colossae.Onesimus, the runaway slave, ran to the largest metropolitan area in the world to disappear. But he could not disappear. Instead, he ran into Paul--who, as you recall, was under house arrest and permitted to have visitors while awaiting his trial before Caesar. Hearing the gospel from Paul, as had his master before him, he repented, and turned to Christ. This was cause for rejoicing. But a cloud hung over our joy. Onesimus was a runaway slave. Death was the normal punishment, so much so that for Philemon to beat his slave to within inches of death would have been regarded a merciful punishment. Onesimus, now converted, sees that he must return to Philemon. Although Philemon might kill him, would certainly hurt him, still he must go back.
Paul more than writing raised many men& women for ministry, by imparting life into them, among them one was Onesimus, who was a run-away slave of Philemon who became his begotten son (a son who carries out fathers will). He was unfaithful and useless for Philemon, but he was very useful for the Kingdom of God. And through his conversion Paul sow a great mission by imparting life into him, and also encourages him to go back to Philemon. Let’s impart godliness in some people , as some are punish for what they do wrong , but some are punished& crushed for whom they belong to, and such suffering experiences attracts people like Onesimus to Christ.
There is no way of knowing what happened to Onesimus after the letter. Ignatius of Antioch mentions an Onesimus as Bishop of Ephesus in the early second century, as Onesimus was not an uncommon slave name, some commentators have suggested a connection between the slave mentioned by Paul and this Bishop of Ephesus.
Significance of this letter was a cause of debate during the British and later American struggles over the abolition of slavery. Both sides cited interpretations of Philemon for support. Modern scholarship has tended to assume that either Paul did undermine slavery in this letter, or that he would have, had circumstances permitted
Paul quotes about Onesimus, “Who once was unprofitable to you, but now is profitable to you and to me:” In some way, Onesimus became profitable to Paul. Perhaps he served as an assistant to Paul during his house arrest. So Philemon’s runaway slave Onesimus was now unprofitable to Philemon, since he had escaped. But he had become profitable to Paul – and by extension, also to Philemon (profitable to you and me). Since Philemon loved Paul, if Onesimus helped Paul he was helping Philemon also.