In Ephesians 6:5-9, the Apostle Paul shows how a Spirit-filled life gives new challenge and meaning to both bondservants (slaves) and masters. For those under authority, the Spirit gives new meaning and motivation to work–it’s mostly about serving Christ. For those in authority, the Spirit challenges them to treat slaves as fellow brothers and sisters in Christ who know the same Lord.
Both of these exhortations are revolutionary for their time, giving unparalleled dignity to slaves and a new paradigm for stewarding power for masters.
But in our time, these verses stand out as a major disappointment (despite their value for understanding work). We might ask, “Why didn’t the Apostle Paul speak against slavery? Instead of accommodating the reality, why didn’t he advocate overthrowing the whole institution in the name of Jesus?”
These questions feel even more pressing in light of the fact that many New World slaveowners justified their abusive and ungodly practice by using these verses. “See,” a slaveowner might reason, “Paul never tried to get rid of the institution, so it must not be inherently evil.”
It’s a difficult question. While I find the answers understandable, they don’t feel satisfying. Nonetheless, here are some top biblical scholars addressing two key issues in answering the question: (1) Differences between Roman slavery and New World slavery, and (2) possible explanations for why Paul didn’t challenge the whole system.
Comparing Roman and New World Slavery
In his commentary on Ephesians, Clinton Arnold writes:
The institution of slavery was an accepted and deeply established part of Roman society. Before the Roman era, slavery was practiced in Greece and throughout the ancient Near East from the earliest times. In fact, slavery was a part of Judaism in every period of its history. Even the patriarchs—Abraham, Isaac, and Jacob—owned slaves (see Gen 12:16; 26:19; 30:43).
The widespread practice of slavery does not give moral justification for its existence. Slavery always involves the ownership of one or more persons by another that constitutes the deprivation of their freedom. When we read Paul’s letters (including Ephesians), we find that he never gives a theological basis for slavery; he assumes its presence in society and helps believers understand what it means to live as a Christian within this socioeconomic institution.
The mention of slavery in a modern context immediately leads people to think of the form of slavery practiced in the New World. Slavery during the Roman Principate, however, was vastly different. It is therefore important that we understand the nature of these differences so that we do not unwittingly import modern ideas of slavery into the biblical context.
There are several distinctive characteristics of Roman-era slavery that should be observed.
(1) Racial factors played no role. Whereas slavery in America in the seventeenth through the nineteenth centuries principally involved the acquisition of black African slaves forcibly taken from their homeland, Roman-era slavery had nothing to do with race or a particular people group.
Roman slaves were of virtually every race of people in the Mediterranean region and involved people from every country. The most common source of slaves in Rome was prisoners of war. When the Roman general Pompey conquered Israel in the first century BC, he brought many thousands of Jewish prisoners to Rome, who became slaves. A smaller number of slaves resulted from the rescue of abandoned infants and from those who sold themselves into slavery because of debt. Some, however, did enter the slave market because they were captured by professional slave traders (see 1 Tim 1:10).
(2) Many slaves could reasonably expect to be emancipated during their lifetimes. A great number of slaves could even expect to be released by the time they were thirty years old. In fact, so many were being released from their servitude in the early first century AD that Caesar Augustus declared thirty years old to be the minimum age for emancipation and then limited how many were freed each year. Owners paid their slaves an occasional sum of money (called a peculium) to reward them for their hard work. This fund was commonly used by the slaves to purchase their freedom. By contrast, slaves in the New World had no hope for manumission and freedom.
(3) Many slaves worked in a variety of specialized and responsible positions. Although some slaves were confined to many years of hard labor in agriculture, manufacturing, or domestic duties, many others served as “doctors, teachers, writers, accountants, agents, bailiffs, overseers, secretaries, and sea captains.” African slaves, by contrast, were seldom entrusted with responsible positions nor did they have the training for any skilled jobs.
(4) Many slaves received education and training in specialist skills. Few opportunities were provided to slaves in the New World to receive general education or skill development training, yet this was a common practice of slave owners in the Roman world. This charity to the slave was beneficial to the master as well as the slave. Goodman notes that masters often viewed it as a wise business strategy to buy and train intelligent slaves and to motivate them to a high quality of workmanship by holding out the prospect of freedom after a specified time.
(5) Freed slaves often became Roman citizens and developed a client relationship to their former masters. It was the common practice for an emancipated slave to gain Roman citizenship. Having gained their freedom, life out from under the provisions and protection of their former masters could be difficult. With their former master now becoming their patron, transition to a more independent life was eased.
In spite of these substantive differences between Roman-era slavery and New World slavery, it is important not to construe this ancient form as more humane or as a morally justifiable economic system. Although we can point to some features that make it appear better than slavery in the Antebellum South of the United States, it still involved the coercive ownership of another person.
Why Didn’t Paul Call for Abolishing Slavery?
Before providing some possible answers, it’s important to note that though Paul did not condemn the practice of slavery, he did not condone it either. Arnold writes,
Because Paul gives instructions to believers on how to live within an unjust social structure does not imply an advocacy of that institution. The way that Paul addresses slavery in 6:5–9 is vastly different from the way that he addresses husband-wife role relations in 5:21–33. Paul never provides a theological rationale for the institution of slavery; yet he does establish a theological basis for male headship and female submission in 5:21–33. His only concern is to provide perspective on how to live as Christians within this empire-wide socioeconomic structure. Just as he never tries to subvert the Roman political structure (in spite of its deficiencies and the perversities of its rulers), so he does not engage in social protest and lead a revolt against the evils of the institution of slavery. The question of why he does not has been much discussed in the literature.
John Stott provides some possible answers:
(1) Christians had no power to overthrow slavery. The first answer is the pragmatic one, namely that Christians were at first an insignificant group in the Empire. Their religion was itself still unlawful, and they were politically powerless.
(2) Slavery was an unfortunate, but integral part, of Roman society. In most cities there were many times more slaves than free people. It would therefore have been impossible to abolish slavery at a single stroke without the complete disintegration of society. As G. B. Caird has put it, ‘Ancient society was economically as dependent on slavery as modern society is on machinery, and anyone proposing its abolition could only be regarded as a seditious fanatic.’ It had to be tolerated a while longer (although, to be sure, that ‘while longer’ lasted much, much too long) as a symptom of what Christians called ‘this present evil age’.
(3) Most slaves were eventually released after a relatively short period. ‘The lack in antiquity of any deep abhorrence of slavery as a social and economic evil may be explained in part’, writes W. L. Westermann, by this fact that ‘the change of legal status out of slavery into liberty by way of manumission was … constant and easy …’ ‘The apostles’ attitude is best explained by the unique way in which the Romans of the first century AD treated their slaves, and released them in great numbers.’  According to the results of Tenney Frank’s research, between 81 and 49 BC 500,000 Roman slaves were freed. So ‘The Roman slave, far from living in perpetual servitude, could look forward to a day of opportunity. It became the common practice of the Romans to free their slaves and then establish them in a trade or profession. Many times the former slave became wealthier than his patron.’  This evidence helps to explain both Paul’s advice to Corinthian slaves, if they could gain their freedom, to seize the opportunity to do so, and his strong hint to Philemon that he should release Onesimus.
(4) The Roman world was already beginning to reform slavery. ‘Sweeping humanitarian changes had been introduced into the Roman world by the first century AD, which led to radically improved treatment of slaves.  Steadily they were granted many of the legal rights enjoyed by free people, including the right to marry and have a family, and the right to own property. ‘In AD 20 a decree of the Senate specified that slave criminals were to be tried in the same way as free men.’  Several emperors introduced liberalizing measures. So more humane legislation was already being introduced in the Empire at the time when the gospel arrived to accelerate and extend the process.
As mentioned above, none of these answers is 100% satisfying. Stott helpfully concludes:
While we cannot defend the indolence or cowardice of … Christian centuries which saw this social evil but failed to eradicate it, we can at the same time rejoice that the gospel immediately began even in the first century to undermine the institution; it lit a fuse which at long last led to the explosion which destroyed it. (emphasis added)
 From the article ‘Slave, Slavery’ by A. Rupprecht in The Zondervan Pictorial Encyclopedia of the Bible, ed. Merrill C. Tenney (Zondervan, 1975), vol. V, p. 458.
 Ibid., p. 459.
 Ibid., p. 458.
 Ibid., p. 459.