Slaves do not have rights - they just serve by doing their duty. Paul knows that there are many slave-masters in Colossae, and some of them now believe in Jesus Christ. Interestingly the Apostle does not challenge the concept of slavery as one of the social habits of the day. Instead he challenges the immoral habit of treating the slaves like dirt; like an object or a possession ... in the same way that he challenged the assumption that it was acceptable to treat women harshly (Colossians 3:19).
The moral basis for good employment relations is that every boss has a boss! God is the master of everybody including the employers. They have to give an account to Him. He is kind and fair to them so they should be caring and fair to their slaves. If they need help, or equipment or food or clothing or any kindness, it must come from the manager. He/she should be the provider in the same way that God provides for them. It is also a workplace application of Jesus' words in Matthew 7:12: "So in everything, do to others what you would have them do to you, for this sums up the Law and the Prophets."
Workplace cruelty is too common. That is not to say that workers ought to take advantage of their employers, or that the boss should not be clear about what is required, or have a strongly focussed workforce. But abuse is not acceptable. Now, note that this verse is not addressed to the workers; it is not intended to stir up dissent or be a bargaining tool for better pay or conditions. Peter says, "Slaves, submit yourselves to your masters with all respect, not only to those who are good and considerate, but also to those who are harsh." (1 Peter 2:18). No! This is written to the masters. They have to settle their own conscience before the Lord. So if you have any management responsibility or you purchase goods or services, remember that the Lord is your 'Boss'. He is seeing how you measure up to His standard. He wants to see you demonstrating His character as you deal with other people. So do a realistic appraisal of yourself; identify your weaknesses, and change! It will be for your blessing, the good of your workers and the glory of God.
© Dr Paul Adams