Why did planters promote Christianity in the slave quarters?

Answer 1

There is an extremely long and fascinating answer to this question, as this is a major side development of the antebellum period in our countries history, but here's the short version.

Slave owners believed they were acting in their slaves best interest by depriving them of and replacing the slave/African culture with their own western one. They believed they were "civilizing" the slaves. This was an attitude known as Southern paternalism, which assumed the slaves were childlike, and unable to take care of themselves. Many slaves discovered life became easier for them when they reinforced this idea, and adopted the servile and submissive attitude portrayed in such old Hollywood films such as Of Mice and Men. Slaves adapted Christianity to their underground cultures and incorporated it into their own traditions and religions, thus birthing new ideas.

Moreover, general knowledge was to be completely suppressed, removed and replaced to make the slave docile. This continued practice over generations, all but guarantees the slave's submission acceptable even to himself and not likely to resist.

Ironically, it was two Christians who liberated the slaves: Abraham Lincoln and Martin Luther King Jr.