According to Douglass, what institution is the "mere covering for the most horrid crimes"? What type of slaveholders are the worst? Why does Douglass think this?

He felt that the religion of the South was "mere covering for the most horrid crimes...a justifier of the most appalling barbarity." Adopted slaveholders were the worst.

Often adopted slaveholders (acquire slaves through marriage) are not used to the rules of slaveholding so they overcompensate by being more cruel.