The problem with the Bible and the New Testament?
Slavery existed in Jesus day and so it continued past the death of the Apostle John about 100-110AD, in fact it still continues today in cheap labor, domestic servitude, sweat shops and voluntary work!
Many Christians employ some of the above mentioned without any qualms and thus they justify much sin, that excuses the world to not see much difference in claimed moral standards?
It is how we treat our workers that is the crucial fact in relation to a days wage that is fare or that we exploit them, believing they are part of our property and this is obvious in the many cults that still exist without challenge today in the mainstream Christian world!
Perhaps the best concept today of slavery and ownership is that of prostitution, since many are not free from being daily exploited men, woman and children and the access of the Internet?
Matthew 13:27-28, Acts 2:18, Romans 6:20, 1 Corinthians 7:23, 2 Peter 2:19, Revelation 19:5.
Ask me and I will tell you! 