Yeap, a lot of slavery in America was perpetuated and validated by religious beliefs

Goes even beyond that. Christianity - specifically, the New Testament verses that extolled the virtue of earthly toil on behalf of a secular lord in exchange for heavenly reward - was leveraged to convince the slaves themselves that their lot in life was justified. And for a great long period of time, it was successful. Even after the Confederacy's back was broken, mobilizing a population that had been wiped into submission for centuries was legitimately difficult. The Freedman's Bureau had a herculean effort put at its feet - to engage, re-educate, and empower millions of newly emancipated black men and women after a lifetime of debasement and degradation.

When you get into why Reconstruction failed, a big part of it was like looking at a spouse in an abusive relationship trying to get out from under a hyper-domineering partner and scaling that sociological problem up to the scale of whole cities and states.