I found a wonderful reading from an article written by William L. Van Deburg, a professor of history and African American studies at the University of Wisconsin, Madison. Van DeBurg claims that Frederick Douglass became more and more religiously liberal the older he got:

It would be a mistake to portray [Frederick] Douglass as a piously conservative Christian. His biographers have correctly noted that he was not orthodox in his doctrine. His belief that religion should be used as an instrument for social reconstruction led him to despise the passive attitude shown by many Negro ministers.

As he progressed in his abolitionist career, Douglass was influenced by those champions of Reason, Transcendentalism, and Unitarianism whose doctrines he had [once] condemned. In an 1848 essay, he noted that the destiny of the Negro race was committed to human hands. God was not wholly responsible for freeing those in bondage. By 1853, he was willing to criticize Henry Ward Beecher’s reliance on God to end slavery. If Beecher had been a slave, Douglass noted, he would have been “whipped … out of his willingness” to wait for the power of Christian faith to break his chains.

Increasingly, enlightenment terminology crept into Douglass’s writings and speeches. Negroes were adjudged to be ‘free by the laws of nature.”

The slaves’ claim to freedom was “backed up by all the ties of nature, and nature’s God.” Man’s [sic] right to liberty was self-evident since “the voices of nature, of conscience, of reason, and of revelation, proclaim it as the right of all rights.”…

Douglass was also affected by the words of transcendentalist preacher Theodore Parker. The [Unitarian] minister’s ideas on the perfectibility of man [sic] and the sufficiency of natural religion were eventually incorporated in the abolitionist’s epistemology. In 1854, Douglass noted, “I heard Theodore Parker last Sabbath. No man preaches more truth than this eloquent man, this astute philosopher.”

The article is titled, “Frederick Douglass: Maryland Slave to Religious Liberal,” and it comes from By These Hands: A Documentary History of African American Humanism, edited by Anthony Pinn (NYU Press, 2001). If you’re a Unitarian Universalist, this whole book is worth reading, if for no other reason than to help you counter the people who say, “Oh, we’ll never get many African Americans in our Unitarian Universalist churches, they’re all Christians.” Pinn demonstrates that there is an important strand of African American humanist thought extending back at least into the 19th C. — if we Unitarian Universalists were more aware of that fact, we might discover that our churches are a lot whiter than they need to be.

Then we could go on to recognize the existence of Latino/a, Lusophone, and Francophone humanists and free thinkers….