If you're looking for copious primary sources to support the broader claims Douglass makes about American churches' support for slavery, they're right here.

Birney wrote this pamphlet (It's about forty pages—that qualified as a pamphlet in the 19th century) to demonstrate to members of various Christian denominations in England that their American counterparts had no intention of getting in the abolition business. Oh, and to beg English churches to use their influence on American churches to bring them around to the idea that slavery might be, you know, bad.

Most of the pamphlet consists of quotes taken from various ministers and church governing bodies in both the North and South. According to these quotes, most churches in the 1830s and 1840s embraced a few main ideas:

• Abolition wasn't any of their business, anyway. It was a civil matter, not an ecclesiastical one. And also we're not touching that with a ten-foot pole, uh-uh, nosireebob.
• Church unity was the most important thing.
• Abolitionists were causing a bunch of "agitation," and who likes to be agitated? Nobody. Can't we all just get along?
• Abolitionists should be lynched. They were pretty strong on that point. Hung "high as Haman" comes up a few times.

Birney wants his English readers to know, though, that it's not all American churches who feel this way—just most of them.