But is it, really?
Colossians 4:1
Masters, treat your slaves justly and fairly, knowing that you also have a Master in heaven.
Exodus 21:16
“Whoever steals a man and sells him, and anyone found in possession of him, shall be put to death.
Ephesians 6:5
Slaves, obey your earthly masters with fear and trembling, with a sincere heart, as you would Christ,
Galatians 3:28
There is neither Jew nor Greek, there is neither slave nor free, there is no male and female, for you are all one in Christ Jesus.
1 Peter 2:18
Servants, be subject to your masters with all respect, not only to the good and gentle but also to the unjust.
Colossians 3:22-25
Slaves, 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.
1 Timothy 6:1-2
Let all who are under a yoke as slaves regard their own masters as worthy of all honor, so that the name of God and the teaching may not be reviled. Those who have believing masters must not be disrespectful on the ground that they are brothers; rather they must serve all the better since those who benefit by their good service are believers and beloved. Teach and urge these things.
Exodus 21:20-21
“When a man strikes his slave, male or female, with a rod and the slave dies under his hand, he shall be avenged. But if the slave survives a day or two, he is not to be avenged, for the slave is his money.
Luke 12:47-48
And that servant who knew his master's will but did not get ready or act according to his will, will receive a severe beating. But the one who did not know, and did what deserved a beating, will receive a light beating. Everyone to whom much was given, of him much will be required, and from him to whom they entrusted much, they will demand the more.
Leviticus 25:44-46
As for your male and female slaves whom you may have: you may buy male and female slaves from among the nations that are around you. You may also buy from among the strangers who sojourn with you and their clans that are with you, who have been born in your land, and they may be your property. You may bequeath them to your sons after you to inherit as a possession forever. You may make slaves of them, but over your brothers the people of Israel you shall not rule, one over another ruthlessly.
Titus 2:9-10
Slaves are to be submissive to their own masters in everything; they are to be well-pleasing, not argumentative, not pilfering, but showing all good faith, so that in everything they may adorn the doctrine of God our Savior.
Ephesians 6:5-9
Slaves, obey your earthly masters with fear and trembling, with a sincere heart, as you would Christ, not by the way of eye-service, as people-pleasers, but as servants of Christ, doing the will of God from the heart, rendering service with a good will as to the Lord and not to man, knowing that whatever good anyone does, this he will receive back from the Lord, whether he is a slave or free. Masters, do the same to them, and stop your threatening, knowing that he who is both their Master and yours is in heaven, and that there is no partiality with him.
1 Corinthians 7:21
Were you a slave when called? Do not be concerned about it. (But if you can gain your freedom, avail yourself of the opportunity.)