For those unfamiliar with Hammon, he is known as the father of African-American literature, being the first published. He was an evangelic Calvinistic Christian who lived his entire life as a slave. The discovered poem, unlike most of his work, focuses on slavery. In it, he defines slavery as a sin--a bold move in the latter half of the 1700s--and reckons it incompatible with genuine Christian witness.
The interview is brief. And like all his work, the poem is theologically rich and thoughtful. Check it out.