Albert J. Raboteau explains what Christianity had to offer in a very bleak situation.
Christianity was a comfort for enslaved people because it gave a sense of meaning into a basically meaningless situation. How do you not despair in terms of the absurdity of being a person who is held as a thing? And Christianity reinforced the sense of the slave’s value as a person, and also gave them some sense of hope that God would intervene in human history to save him as he had intervened in human history before. So the concept of the divine providence intruding into human history to deliver his people was an extremely important buttress to their sense of hope.
Slave masters sort of glimpsed this every now and then. Sometimes the slaves would say – particularly during the Civil War: “Are you praying for victory for the south?” And slaves would say, “We’re praying for God’s will to be done”. And the master would say, “No, don’t pray that way. Pray that the South will win.” He had no control over what they were praying for. So the sense of hope, and particularly the notion that God intervenes to lift up the lowly and to cast out the mighty, was an extremely important buttress for their sense of hope in a situation that was often very, very bleak.