Philemon 8-11
In the eighth verse of his epistle to Philemon, Paul clearly reveals the purpose of his writing. Philemon’s slave, Onesimus, had apparently ran away from Philemon. He had met Paul, and Paul had converted him to Christ (vs 10). As Paul put it, “who once was unprofitable to you, but now is profitable to you and to me” (vs. 11).
While Paul had the authority to command Philemon in his treatment of the slave, he did not exercise that prerogative. Instead, he appealed to Philemon as a faithful and loving child of God.
Onesimus had broken the law in running away. His return could have been dangerous for him, but Paul was convinced that the love of Christ, present in Philemon, would moderate his response to Onesimus’ return — especially since Onesimus was now a brother in Christ.
No matter our relative positions in life, when we are Christians, we are brethren.