In _Twelve Years a Slave_ by Solomon Northup, a free black who was captured
and sold to a plantation in Louisiana, Northup details several occasions
where owners/other people he was lent out to would quote the Bible
supporting the institution of slavery.  One verse which I recollect can be
found in Luke 12, verse 47-48:  "The servant who knows what his master wants
him to do, but does not get himself ready to do it, will be punished with a
heavy whipping.  But the servant who does not know what his master wants,
and does something for which he deserves a whipping, will be punished with a
light whipping. ..."

I'm starting up my Huck Finn unit next week, and I try to make sure my
students realize what whites thought of blacks during that time period.
Whites in the South would never see/hear anything which promoted the idea of
blacks as human, much less deserving of the same rights whites enjoyed.  And
only part of this societal blindness was the role the church played in it.
After discussing southern society of the time, and emphasizing the horrors
slaves continually endured, Huck's decision to free his friend becomes that
much more amazing/inspiring.  Here's an uneducated white trash kid who has
been taught that abolitionists go to hell to burn deciding to suffer that
rather than let a slave remain in his "proper" place.

When my kids understand this, Mark Twain's "radicalness" becomes clear and a
seemingly aimless novel (once Huck and Jim go past Cairo) becomes the
anti-slavery narrative I've been telling them it  is ...