Bondservants, obey in everything those who are your earthly masters, not by way of eye-service, as people-pleasers, but with sincerity of heart, fearing the Lord.  Whatever you do, work heartily, as for the Lord and not for men,  knowing that from the Lord you will receive the inheritance as your reward. You are serving the Lord Christ.  For the wrongdoer will be paid back for the wrong he has done, and there is no partiality.
 Masters, treat your bondservants justly and fairly, knowing that you also have a Master in heaven.
Colossians 3:22 to 4:1
This is a challenging subject! One, because after the abolition of slavery we can think that we have done and said all that needs to be done and said on the subject, when in fact all we have done is to begin to scratch the surface. Two, because slavery is still very much prevalent in our world today.
Can I recommend the book, ‘Slave’ by Mende Nazer, the true story of a girl’s lost childhood and her fight for survival.
I believe this statement is true and right,
 All Scripture is breathed out by God and profitable for teaching, for reproof, for correction, and for training in righteousness,  that the man of God may be complete, equipped for every good work.
2 Timothy 3:16-17
Paul is speaking about the Old Testament when he wrote this to young Timothy, but we also know that what he says extends to all Scripture, inclusive of the New Testament and his own writings.
 And count the patience of our Lord as salvation, just as our beloved brother Paul also wrote to you according to the wisdom given him,  as he does in all his letters when he speaks in them of these matters. There are some things in them that are hard to understand, which the ignorant and unstable twist to their own destruction, as they do the other Scriptures.
2 Peter 3:15-16
But how can a passage giving instructions to slaves and masters be, “profitable for teaching, for reproof, for correction, and for training in righteousness?” What can this passage possibly say to us in the twenty-first century when almost all governments oppose the idea of slavery. Surely we cannot be preaching on a Sunday to congregations that include slaves and masters.
Are there ethical principles that can be taken from Paul’s instructions to slaves and masters in the first century that are relevant and instructive for us in the twenty-first, that bear some degree of resemblance to the slave-master relationship?
The general way out is to ignore the slave, master context and bring it up to date by using the terms employer and employee. Although this may make it sound relevant it is not what the passage is about. Also the context is not fixed as some countries are governed by laws for employers and employees whereas other countries are definitely not! So this is not an easy subject to get your theological, moral and ethical head around.
Before we go any further we have another hurdle to leap in that many have argued that the wider subject of submission found in the preceding verses morally cannot and should not apply to slaves and masters as it’s outdated.
The argument being, the argument for why wives should submit to husbands the same as the argument for why slaves should submit to masters. While others argue the opposite.
Craig Keener, for example, says that “modern writers who argue that Paul’s charge to wives to submit to their husbands ‘as to Christ’ is binding on all cultures must come to grips with the fact that Paul even more plainly tells slaves to ‘obey’ their masters ‘as they would Christ’ (Ephesians 6:5)? If one is binding in all cultures, so is the other.”
So this is going to be difficult to get through without treading on someone’s toes. Here goes.
Scripture is known to accept relationships and situations without condoning them as permanent ideals (see Matthew 19:8, 1 Corinthians 6:1-8). Paul’s recommendation for how slaves and masters should relate to each other does not assume that slavery is a good thing.
“The Bible does not approve or command slavery any more than it approves or commands persecution of Christians. When the author of Hebrews commends his readers by saying, ‘You joyfully accepted the plundering of your property, since you knew that you yourselves had a better possession and an abiding one’ (Hebrews 10:34) that does not mean the Bible supports the plundering of Christians’ property, or that it commands theft. It only means that if Christians have their property taken through persecution, they should still rejoice because of their heavenly treasure, which cannot be stolen. Similarly, when the Bible tells slaves to be submissive to their masters, it does not mean that the Bible supports or commands slavery, but only that it tells people who are slaves how they should respond.”
The idea of slavery is not grounded in creation but is a distortion resulting from the fall. Marriage and male headship, on the other hand, are part of the original created order that precedes the fall. As Wayne Grudem also said, “people who abolished slavery, based on an appeal to biblical principles . . . were abolishing something evil that God did not create. But Christians who oppose male headship in marriage and the church are attempting to abolish something good, something that God did create. The examples are simply not parallel.”
On several occasions in the New Testament the seeds for getting rid of slavery are sown. This is especially seen in Paul’s words to Philemon. Nothing in the New Testament, however, suggests that the same was envisioned for the relationship between husbands and wives.
No permanent moral command is used with reference to the institution of slavery in Paul’s writings. He is obviously adapting to a temporary and ultimately wrong social ideal but such is not the case with his instruction to husbands and wives which is consistently grounded not in culture but in creation or in the relationship of Christ to the Church.
Finally, Paul explicitly sees and endorses the possibility of a slave obtaining freedom (1 Corinthians 7:21). He never says anything comparable to this with regard to wives and submission to their husbands. So these are the best guidelines in a very difficult situation.