Slavery is, obviously, supported in the Bible. Slavery was defended in the Old South by good white Christians who relied on the Bible to justify their immoral, unjust, and oppressive culture. What many don't realize, though, is how extensively intertwined Christianity and slavery were in the Old South. In many ways, the Civil War as a much a defense of Christianity as it was a defense of slavery: the elimination of slavery meant the elimination of an institution grounded in Christian doctrine.
Read Article: Slavery & Christianity in the Old South: Blending Culture and Christianity

Those southern Christians were not “real Christians”.
As an ancient Roman once wrote: if the oxen and sheep had a deity, it would have horns and hooves.
The problem with being an atheist is that when we want to do @#%& like this we don’t have any religious scriptures to provide cover.
Ron: Yes, and it’s funny how that makes engaging in the exact same activities and actions “immoral.”
Americans even still debate why the war was fought. Many a revisionist says it was about state’s rights. Others insist it was over slavery. The latter have history on their side.
http://www.npr.org/blogs/itsallpolitics/2011/04/12/135353655/slavery-not-states-rights-was-civil-wars-cause