That passage isn't a discussion on treating slaves, its about the individual's responsibility to serve God:"The servant will be severely punished, for though he knew his duty, he refused to do it (Luke 12:47)" Jesus says, "BEAT THE F' OUT OF YOUR SLAVES!"
KJV: "Be Ready for Service
35Let your loins be girded about, and your lights burning; 36And ye yourselves like unto men that wait for their lord, when he will return from the wedding; that when he cometh and knocketh, they may open unto him immediately. 37Blessed are those servants, whom the lord when he cometh shall find watching: verily I say unto you, that he shall gird himself, and make them to sit down to meat, and will come forth and serve them. 38And if he shall come in the second watch, or come in the third watch, and find them so, blessed are those servants.
39And this know, that if the goodman of the house had known what hour the thief would come, he would have watched, and not have suffered his house to be broken through. 40Be ye therefore ready also: for the Son of man cometh at an hour when ye think not.
41Then Peter said unto him, Lord, speakest thou this parable unto us, or even to all? 42And the Lord said, Who then is that faithful and wise steward, whom his lord shall make ruler over his household, to give them their portion of meat in due season? 43Blessed is that servant, whom his lord when he cometh shall find so doing. 44Of a truth I say unto you, that he will make him ruler over all that he hath. 45But and if that servant say in his heart, My lord delayeth his coming; and shall begin to beat the menservants and maidens, and to eat and drink, and to be drunken; 46The lord of that servant will come in a day when he looketh not for him, and at an hour when he is not aware, and will cut him in sunder, and will appoint him his portion with the unbelievers. 47And that servant, which knew his lord's will, and prepared not himself, neither did according to his will, shall be beaten with many stripes. 48But he that knew not, and did commit things worthy of stripes, shall be beaten with few stripes. For unto whomsoever much is given, of him shall be much required: and to whom men have committed much, of him they will ask the more."
This is about the Laws of Warfare, prisoners of war who surrender may be forced to do labor. That law stands to this day, it's in the the Convention relative to the Treatment of Prisoners of War, Geneva July 27, 1929 says the same in Articles 27-34.And here's a gem:(Deuteronomy 20:10-14) "As you approach a town to attack it, first offer its people terms for peace. If they accept your terms and open the gates to you, then all the people inside will serve you in forced labor. But if they refuse to make peace and prepare to fight, you must attack the town. When the LORD your God hands it over to you, kill every man in the town. But you may keep for yourselves all the women, children, livestock, and other plunder. You may enjoy the spoils of your enemies that the LORD your God has given you."
GOD has GIVEN YOU these women and children to be your SLAVES.
Face it, God believes slavery is VALID and MORAL