In the past, people tried to use the Bible to justify slavery. There are many passages, two which we will focus on, that contradict this past claim.
In Deuteronomy 15:1-18, we get a description of the Sabbatical Year, the 7th year or the year of rest. It was during this year that the Hebrews who had sold themselves into slavery were to be freed. That makes this slavery more like a 6 year indentured servitude. The only exception was if someone chose to stay with their master permanently. In other words, these slaves had a choice. God also tells the people of Israel in this passage that they are to remember that they were once slaves in the land of Egypt.
The other passage is Paul’s Letter to Philemon. Philemon’s slave, Onesimus, fled his master and came to Paul. In his letter, Paul asks Philemon not only to take Onesimus back, but to go so far as to free him. It is worth noting that in some Christian traditions, Onesimus is said to be an Apostle and a bishop of the church. Thus, presumably, Philemon did free him.
The Bible tells us the story of many people, both good and bad. We can hardly say it condones slavery. If anything, it encourages the freeing of slaves. It certainly teaches us to treat others well and with respect.