Eph 6:9 And you, masters, do the same things to [bondservants], giving up threatening, knowing that your own Master also is in heaven, and there is no partiality with Him.
Col 4:1 Masters, give your bondservants what is just and fair, knowing that you also have a Master in heaven.
There is a wonderful equality in the order that God has created through His Son. We may be in a position of power and influence over others, but we must never forget that however promoted we become in this world, God reigns over all. It is one of the most important lessons a person learns, that no matter his status, we all have to answer to the “the judge of all”. It is this realisation that should ensure that we treat those over whom we have power with equity and fairness.
Paul does not seek to undermine the authority that a ‘master’ would have over his slaves. Instead, he teaches that his earlier advice to slaves also applies to masters: “Whatever you do, do it unto the Lord.” The dealing a master must have with his slaves, is as if whatever he was doing was unto the Lord. It is sobering to realise that we are to live to others, whether they are our inferior or superior, as if we are dealing with the Lord. That should keep us humble whatever our role is. Paul makes two specific recommendations: ensure that you give them what is fair and just, and secondly, cease from threatening. Threats are an easy way to attempt to control others, but they operate by fear not by love. Threats should have no place in our dealings with anyone in the world, and even more so with those in the church.
Paul does not seek to undermine the social structure that existed in the Roman empire at this time regarding slavery. Our calling as Christians is not to seek political change, but rather the change of heart in individuals that comes with the preaching of the gospel. Political change so often follows the righteousness that develops in a society as a natural consequence of the reformation of individuals. Sadly, even after the efforts in the 18th and 19th centuries slavery has still not been eliminated from this world. And finally, returning to the equality we mentioned at the beginning, “For he who is called in the Lord while a slave is the Lord's freedman. Likewise he who is called while free is Christ's slave.” (1Cor 7:22)