Slaves were an important part of Roman society. In cities such as Ephesus, up to a third of the population was made up of slaves working in households and serving not only as domestic servants but also as teachers and physicians. Slaves had minimal rights and faced the ever-present threat of abuse and oppression.

Paul did not condone slavery; neither did he lead a revolution against it. But as illustrated in his epistle to Philemon, Paul encouraged Christians living in a society that had institutionalised slavery to act in a Christian manner so that the system could be replaced by a more equal and just society. Paul's approach, as New Testament scholar C. F. D. Moule put it, was ″not to batter but to undermine″. There were many slaves in the early church, and for Paul to address them before their masters would have been a radical move in itself.

Slaves are to submit to their masters in deference to God's order (″as you would obey Christ″, Ephesians 6:5). They may have hated their masters, especially if their masters were demanding or cruel, and served grudgingly or cut corners in their work. The Greek word in verse 6, translated as ″when their eye is on you″, is literally ″eye-service″. Slaves who hated their masters would work hard only when the boss was around, perhaps just to score brownie points.

For the Christian slave, all this was to change because of Jesus. Each of Paul's specific instructions to slaves focuses on Christ. They should obey their masters just as they would obey Christ (v. 5). They should serve as ″slaves of Christ″ (v. 6). They should serve wholeheartedly as if they were serving Christ (v. 7). And they should always remember that it is the Lord who will reward (and punish) everyone, slave and master alike (v. 8). This core relationship with Christ would make the Christian slave radically different.

The Christian slave would obey and respect his earthly master, provide sincere and diligent service, and seek to do God's will from his heart. As John Stott put it, he would have a ″higher preoccupation″ amid his more mundane tasks (v. 6). Such a slave would serve his earthly masters well because in his heart he was serving the heavenly Master. He would be a great witness to his master that his heavenly Master ″did not come to be served, but to serve″ (Mark 10:45).