Just as the human institution of marriage and the concomitant institution of the parent-child relationship will pass away in the consummated new creation, so will the institution of slavery. In the inaugurated form of the new creation, all Christians, including slaves and masters, are spiritually equal, though each have particular roles they must continue with in “this world [that] is passing away” (1 Cor. 7:31).
How does the above discussion of slaves and masters in my comments on Col. 3:22–4:1 bear upon the question of slavery in general and Paul’s own view of the institution of slavery? First, Paul has qualified the slave-master relationship by saying that both have a Lord in heaven who will judge them for the good and bad that they do. In addition, Paul addresses both as accountable parties who are to yield voluntary obedience to the Lord in the master-slave relationship. Especially significant is that slaves are viewed as responsible parties, who are to yield responsible and sincere obedience to masters and above all faithful obedience to the Lord, since it is the Lord whom they ultimately serve.
Second, Paul views the slave Onesimus, mentioned in Col. 4:9, to be a “faithful and beloved brother,” who is a full-standing member of the church at Colossae (i.e., “who is one of your number”; so likewise Philem. 16, where Paul also calls him a “beloved brother”). Onesimus is also Paul’s “child” (Philem. 10). Consequently, though Onesimus is a slave in his worldly calling, he is equal in brotherhood to his other Christian brothers and sisters. In this respect, Paul further significantly qualifies the institution of slavery by saying that within the new-covenant community distinctions of “slave” and “free” have been abolished with respect to inheriting salvation and spiritual equality in fellowship (Col. 3:11; Gal. 3:28; cf. Pao 2012: 283). The nearest that Paul gets to a notion of emancipation is 1 Cor. 7:21: after saying that a person should “remain in that condition in which he was called” (1 Cor. 7:20), he asks, “Were you called while a slave? Do not worry about it; but if you are able also to become free, rather do that.” This probably is to be understood against the Roman background in which deserving slaves in urban areas were regularly offered manumission as a reward. Paul is telling slaves to take advantage of such offers (MacDonald 2000: 163).
Third, masters are to treat slaves “justly and fairly” (Col. 4:1), which is an ever-present and governing ethic for them to follow.