The Bible does not specifically condemn the practice of slavery. It gives instructions on how slaves should be treated (Deuteronomy 15:12-15; Ephesians 6:9; Colossians 4:1). The Bible does not outlaw slavery altogether. However, the problem is that many individuals mistakenly interpret this as the Bible condoning all forms of slavery.
What many fail to understand is that slavery in biblical times was very different from the slavery that was practiced in the past few centuries in many parts of the world. The slavery in the Bible was not based exclusively on race. People were not enslaved because of their nationality or the color of their skin. In Bible times, slavery was more a matter of social status. People sold themselves as slaves when they could not pay their debts or provide for their families. In New Testament times, sometimes doctors, lawyers, and even politicians were slaves of someone else. Some people actually chose to be slaves so as to have all their needs provided for by their masters.
In contrast, the slavery of the past few centuries was often based exclusively on skin color. In the United States, many black people were considered slaves because of their nationality; many slave owners truly believed black people to be inferior human beings. The Bible most definitely does condemn race-based slavery!
Consider the slavery the Hebrews experienced when they were in Egypt. The Hebrews were slaves, not by choice, but because they were Hebrews (Exodus 13:14). The plagues God poured out on Egypt demonstrate how God feels about racial slavery (Exodus 7-11). So, yes, the Bible does condemn some forms of slavery. At the same time, the Bible does seem to allow for other forms. The key issue is that the slavery the Bible allowed for in no way resembled the racial slavery that plagued our world in the past few centuries.
In addition, both the Old and New Testaments condemn the practice of “man-stealing”, which is what happened in Africa in the 19th century. Africans were rounded up by slave-hunters, who sold them to slave-traders, who brought them to the New World to work on plantations and farms. This practice is abhorrent to God.
In fact, the penalty for such a crime in the Mosaic Law was death: "Anyone who kidnaps another and either sells him or still has him when he is caught must be put to death, whether." (Exodus 21:16). Similarly, in the New Testament, slave-traders are listed among those who are “ungodly and sinful” and are in the same category as those who kill their fathers or mothers, murderers, adulterers and perverts, and liars and perjurers (1 Timothy 1:8-10).
Another crucial point is that the purpose of the Bible is to point the way to salvation, not to reform society. The Bible often approaches issues from the inside out. If a person experiences the love, mercy, and grace of God by receiving His salvation, God will reform his soul, changing the way he thinks and acts. A person who has experienced God’s gift of salvation and freedom from the slavery of sin, as God reforms his soul, he will realize that enslaving another human being is wrong. A person who has truly experienced God’s grace will in turn be gracious towards others. That would be the Bible’s prescription for ending slavery.