Douglass realizes that his tone in the body of his narrative may have resembled a condemnation of all religion. The appendix is designed to set the record straight: Douglass is not opposed to all religion; he only takes issue with the religion that slaveholders use to justify their inhumane actions. In fact, Douglass “loves the pure, peaceable, and impartial Christianity of Christ.” It is only the distortion of Christianity that he experienced as a slave that he hates.
Douglass’s references to divine providence show him to be a firm believer in a benevolent, Christian God. What he finds intolerable is certainly not Christianity.It's the hypocritical distortion of Christianity, the religion in which he believes and worships, to condone the atrocities of slavery.
Douglass condemns the hypocrisy of so-called Christians who brutally beat slaves, use them for prostitution, disband their families, and steal from their fellow humans. Oftentimes, Douglass notes, the ill-gotten gains of slavery are funneled back into the church. Douglass uses Bible verses to support his arguments, and compares the immoral slaveholding Christians to the Pharisees who persecuted Christ. He also invokes abolitionist poetry and ironically lampoons Southerners’ own songs in order to drive his point home.
Slavery and the corrupt church help sustain one another, and, in turn, amplify the vices of each institution. Douglass’s treatment of the issue highlights the irony of a situation in which those who are supposedly the most pious encourage the most inhumane activity.