Christianity was used to justify slavery for hundreds of years and numerous prominent Christian pastors in the South gave impassioned speeches that heavily motivated secession. The Jim Crow South was also heavily motivated by prominent Christian leadership.
This Gospel civilization, many believed, didnt just permit slavery it required it. Christians across the Confederacy were convinced that they were called not only to perpetuate slavery but also to perfect it. And they understood the Bible to provide clear moral guidelines on how to properly practice it. The Old Testament patriarchs owned slaves, Jewish law clearly assumed its permissibility and the Apostle Pauls New Testament letters repeatedly compelled slaves to be obedient and loyal to their masters. Above all, as Southerners never tired of pointing out to their abolitionist foes, the Gospels fail to record any condemnation of the practice by Jesus Christ.
There is consequently a fascinating, if unsettling, paradox in the efforts of slaveholders to fulfill what they considered divinely imposed duties toward their slaves. Southern Christians believed that the Bible imposed on masters a host of obligations to their slaves. Most fundamentally, masters were to view slaves as fully members of their own households and as fellow brothers and sisters in the Lord. Therefore, as the South Carolina Methodist Conference declared before the war, masters sinned against their slaves by excessive labor, extreme punishment, withholding necessary food and clothing, neglect in sickness or old age, and the like.
https://opinionator.blogs.nytimes.com/2012/04/27/the-south-the-war-and-christian-slavery/?mcubz=3
The bible includes instruction on how to sell your children into slavery, btw.