Methodist Church (1); denomination (2)

The Methodist Church, founded by John Wesley, is a large denomination, or group of churches bound by shared beliefs and organizational ties, within Protestantism. It's hard to keep track of 'em all, but they each have their own quirks.

Communion (2); bread and wine (4); sacraments (6); the Lord's table (10); sacramental elements (10); cup (11)

Douglass describes the process of taking Communion, which is a sacrament—a holy act in Christianity performed with the purpose of remembering God's promises. During Communion, Christians consume bread and wine to remember Christ's body and blood. The bread and wine are the sacramental elements, and the wine is sometimes referred to as the cup. Communion is taken at or from the Lord's table, which typically stands near the front of the church. Never a dull moment at church, eh?

colored (5)

Well into the 20th century, "colored" was a term used to describe black people. While generally intended at the time to be descriptive and not insulting, it's off limits today.

deacon (11)

It might sound like a sci-fi character, but this is just a position held by lay members (or non-clergy members) of the church that allows them to do certain things, like serve Communion.

blessed Saviour (12); dear Redeemer (41)

Both of these are references to Jesus Christ. He has plenty more nicknames, but Douglass sticks to just his fave few.

precious blood (12)

A reference to the wine (remember Communion?), which symbolizes Jesus' blood shed on the cross.

"Stu-boy!" (27)

A reference to one of the insulting ways slaveholders and overseers referred to slaves. Spoiler alert: there were a lot of them.

Providence (37)

A term for God. And the capital of Rhode Island.