I learned something watching AM Joy
https://historyengine.richmond.edu/episodes/view/3535
Slave owners had many justifications for why holding people in bondage was acceptable. From the idea that African Americans were a lesser race who needed taking care of by white patriarchs to the economic justification, slave owners were always trying to find new ways to dispute those who disagreed with their choice to hold others in captivity. Charleston slave holders were no exception in attempting to find justifications to mask their guilt. Often, religion came into play, on both the slavery and anti-slavery sides of the debate. In 1835, at the end of two long articles about religion and slavery in the Charleston Mercury, it was said that both the Old and New Testament give permission to hold others as slaves. In the Old Testament, God and the Patriarchs approve. As for the New Testament, Jesus and the Apostles show that slavery is permissible. Therefore, slavery, to those who wrote the article, was not an anti-Christian institution. It was just the opposite. Furthermore, they added, it is impious to say slavery is anti-Christian because such a conclusion contradicted God.
Such extremist beliefs were common in the slavery/antislavery debate. Slaveholders believed that slavery would liberate Africans from their savage-like ways, especially if they were infused with Christianity. As religion ran deep through slavery, white Christian slaveholders argued that slavery was a necessary evil because it would control the sinful, less humane, black race.