But as for servants, what can we say more than that the slave act with good will toward his master, with the fear of God, though his master be impious and wicked; yet the servant should not comply with requests or commands to worship other gods. And the master should love his servant, although he be his superior. Let him observe in what ways they are equal, even as he is a man. And let him who has a believing master love him both as his master, and as of the same faith, and as a father, but still with the preservation of his authority as a master…. In like manner, let a master who has a believing servant love him as a son or as a brother, on account of their communion in the faith, but still preserving the difference in status between the two.
Love him both as his master, and as of the same faith, and as a father, but still with the preservation of his authority as his master: "not as an eye-servant, but as a lover of his master; as knowing that God will recompense to him for his subjection."
Paul implies that God has created all persons to be freeborn and says this to keep masters from arrogance. Slavery is itself a sign of iniquity in the world, of the curse of Cain. In fact, the wise person is always free, though a slave outwardly, while it is foolish sinners who are the true slaves. .
And see how always he sets down the names, "wives, children, servants," being at once a just claim upon their obedience. But that none might be pained, he added, "to your masters according to the flesh." Thy better part, the soul, is free, he saith; thy service is for a season. It therefore do thou subject, that thy service be no more of constraint. "Not with eye-service, as men-pleasers." Make, he saith, thy service which is by the law, to be from the fear of Christ. For if when thy master seeth thee not, thou doest thy duty and what is for his honor, it is manifest that thou doest it because of the sleepless Eye. "Not with eye-service," he saith, "as men-pleasers"; thus implying, "it is you who will have to sustain the damage." For hear the prophet saying, "God hath scattered the bones of the men-pleasers." (Ps. liii. 6, Sept.) See then how he spares them, and brings them to order. "But in singleness of heart," he saith, "fearing God." For that is not singleness, but hypocrisy, to hold one thing, and act another; to appear one when the master is present, another when he is absent. Therefore he said not simply, "in singleness of heart," but, "fearing God." For this is to fear God, when, though none be seeing, we do not aught that is evil; but if we do, we fear not God, but men. Seest thou how he bringeth them to order?
Slaves are to be admonished in one way, masters in another. That is, slaves are to be admonished to consider always the lowliness of their condition; masters, ever to bear in mind their own nature, namely, that they have been created equal to their slaves. Slaves are to be admonished not to despise their masters, lest they offend God by their proud opposition to his ordinance. Masters are also to be admonished that they offend God by priding themselves on his gift to them, without realizing that they who are held in subjection by reason of their state of life are their equals in virtue of their common humanity.
[AD 100] Didache on Colossians 3:22