Onesimus, a slave, had run away from his master, Philemon, of Colossae, and had hidden himself in Rome, where he came under Paul's influence and was converted to Christianity.

In his loyalty to the civil law, Paul felt that Onesimus, in fulfillment of his Christian duty, should return to his master. He had probably robbed Philemon, and should make at least this restitution. He therefore sent Onesimus back to Colossae under the escort of Tychicus, who carried this letter to Philemon.

Paul did not attack slavery as an institution. He did not charge Philemon to emancipate his slave. For the final extinction of slavery he relied on the spirit of the Gospel, and on its principle that all men are brethren in Christ and alike servants of the one heavenly Master.

After salutations to Philemon and his household, and acknowledgments of Philemon's loving service to the Church and to himself, he introduces the main subject of the letter. He asks as a personal favor that Philemon will kindly receive Onesimus. He praises the ministries of the latter to himself, playing upon his name, “once unprofitable but now profitable,” and expressing his desire to keep him with himself. This, however, he will not do without Philemon's consent. If Philemon shall see fit to retain him in his own service, he will find him, as a Christian, far more valuable than he was as a pagan slave. Perhaps his flight was divinely permitted, in order that he might return to his master as a Christian brother. He hints delicately at Onesimus' possible thefts, offering his personal security for the amount stolen, though intimating that Philemon is already in his debt for his own conversion. He is sure that Philemon will comply with his request. He thinks he will soon be released from prison, and asks his friend to prepare him a lodging in view of his visit.

The epistle has always been celebrated as a model of Christian tact and courtesy. Paul waives his apostolic right to command, and throws himself upon the appeal of Christian friendship, backing it with a delicate allusion to his sufferings for the Gospel's sake. Without palliating Onesimus' fault, he throws round him the protection of his own confidence and esteem. He softens the phrases which describe the slave's flight and theft. He does not say “he ran away,” but “he was separated from thee.” He does not say “he stole,” but, “if he hath wronged thee or oweth thee aught.” With exquisite tact he assumes that Philemon will regard Onesimus' ministries to the prisoner as his own, and will rejoice in them as an expression of his own affection.

The letter has often been compared with the younger Pliny's epistle to Sabinianus, written under similar circumstances. Doddridge remarks that although antiquity furnishes no example of the epistolary style equal to Pliny's letter, Paul's letter to Philemon is far superior as a human composition. Dr. Davidson says: “It puts Paul's character in a light which none other of his writings exhibit. The qualities which dictated its composition are eminently attractive. Dignity, generosity, prudence, friendship, politeness, skillful address, purity, are apparent. Hence it has been called, with great propriety, 'the polite epistle.' True delicacy, fine address, consummate courtesy, nice strokes of rhetoric, make it a unique specimen of the epistolary style. It shows the perfect Christian gentleman.” Ewald: “Nowhere can the sensibility and warmth of tender friendship blend more beautifully with the higher feeling of a superior mind, nay, of a teacher and apostle, than this brief and yet so eminently significant letter.” Renan: “A little chef-d'oeuere of the art of letter-writing.” Calvin: “Though he handleth a subject which otherwise were low and mean, yet after his manner he is borne up aloft unto God. With such modest entreaty doth he humble himself on behalf of the lowest of men, that scarce anywhere else is the gentleness of his spirit portrayed more truly to the life.” Maclaren: “Without thought of effect, and with complete unconsciousness, this man beats all the famous letter-writers on their own ground. That must have been a great intellect, and closely conversant with the Fountain of all light and beauty, which could shape the profound and far-reaching teachings of the epistle to the Colossians, and pass from them to the graceful simplicity and sweet kindliness of this exquisite letter; as if Michael Angelo had gone straight from smiting his magnificent Moses from the marble mass, to incise some delicate and tiny figure of Love or Friendship on a cameo.”