This, the fourth of the personal letters of Paul, differs from the other three, as well as from all other epistles of Paul, in that it is neither doctrinal, nor intended for general church instruction. It has its interest in that it shows by a particular example the application of the great principles of Christian brotherhood to social life. It is written to Philemon, an active Christian of Colosse, a convert of Paul, in behalf of Onesimus, a runaway slave of Philemon, who had found refuge in Rome, had in some way been brought under Paul's instruction during his first Roman imprisonment, and had been brought to Christ. In Col 4:9 he is mentioned as belonging to Colosse, commended as a faithful and beloved brother who had been of great service, and it is there stated that he would return from Rome to his old home along with Tychicus, while this epistle explains the occasion of his return, and throws a practical light on the new relations of master and slave, which could not be done by precept alone.
A few words concerning ancient slavery will assist in an understanding of the lesson of the epistle. Slavery was universal. Aristotle, one of the most enlightened of the Greeks, held that the Creator had made the majority of the human race for slavery. Even the Mosaic law permitted the relation, but mitigated the condition of the slave by protective regulations which made Jewish slavery far the mildest in the world. Under the Roman law the slave was not considered a man, but a chattel without any civil rights whatever, completely at the mercy of his master. The master could sell him, give him away, torture him, crucify him, put him to death, even feed him to the fishes, and there was no law to interfere in his behalf. But when Christ came he introduced new relations between man and man. All in the church were a brotherhood. In Christ Jesus there was neither bond nor free, male nor female. All stood on a footing of equality before the Lord; all were brethren; all God's children, and to be bound to each other by the ties of brotherly love.
Such revolutionary ideas were sure in the course of time to destroy the condition of slavery, but in the meanwhile, Christianity sought to prepare men for the revolution before it was declared, and hence the relation was continued under new regulations. The servant was to continue to render faithful service to a master who was a brother beloved, and the master was to love and trust his servant as a brother, and to do unto him as he would be done by in such a relation. Hence in the early church thousands of masters and slaves met on an equal footing and often the slaves were the bishops who ruled the church and watched over the spiritual welfare of their masters.
Onesimus, an unconverted slave of Philemon, had fled, whether after or before his master's conversion, is unknown. When he was converted the principles of Christian teaching would require him to return, but the conditions of his return are explained in the affectionate letter which he carries back to Philemon. He returns a servant, but as a more than servant, "a brother beloved, both in the flesh, and in the Lord," and Philemon is desired to so receive him in a tender appeal to his consciousness of how much he owes to him who asks. He is reminded that Onesimus is Paul's own son in the Gospel, as well as himself. A sense of the fault is exhibited, and forgiveness for the offender is required, not by the authority of apostolic power, but of love.
This epistle must have been written about the same time as that to the Colossians, and was carried by the same messengers. Its genuineness is accepted by almost all critical authorities, the rationalist Baur being the only notable exception.