History of the Black church.
The history of the Black church as a political force goes back to the days of slavery. Initially Christianity was imposed on African slaves, the stated purpose was to save the souls of "savages" from eternal damnation, functionally, though. the religion acted as a means of control. The bible was quoted and twisted to justify slavery and the inferiority of black people. White slave masters thought that religion might make slaves more docile. In any case, it helped repress and destroy the African cultural traditions the slaves brought with them to the Americas.
But, then a few good things happened: slaves and freedmen began to lead their own Christian congregations. Being mostly Baptists they had to learn to read since every Baptist must read the bible for his or herself. The word of God, as it appears in the bible, reached the enslaved people who read it and they were able to reinterpret the word in a way that pointed to freedom. This process was accelerated after the civil war. The music and structure of church services was infused and improved by the addition African traditions. The Black church came in to being. It is a religious, cultural, artistic, educational and political entity.
Why is the Black Church so political?
Not all black churches are "so political" but many are. As recently as 50 years ago laws in parts of this country prevented black people from congregating in large groups. This made political organizing very difficult. What was allowed, however, were church services --so the church served a dual role as religious body and political organization. The Baptist churches have "separation of church and state" as one of their core principals... but, there is no conflict here because "Separation of Church and state" means that the Church should not administer law and that there should be no "official state religion." But, political decisions are often moral -- so, yes, churches can and will take positions and even do work on these matters. The Civil rights movement would not have happened had it not been for the Black church. Smaller local matters are also taken on by the church-- like opposing police brutality, petitioning for equal schools and equal city services and much more. (What remains unacceptable is directly endorsing a political candidate or telling people how to vote.)
Do we still need a Black church?
"Eleven o'clock Sunday morning is the most segregated hour in America."
--Martin Luther King, Jr.
Martin Luther King's words are still true today, though some of the segregation is waning. One reason why it is taking so long for churches to desegregate is becuase the segregation is related to residential segregation. And most people still live in neighborhoods that are very much mono-racial. In addition, the people who go to church may tend to be more conservative, and so less receptive to integration. In the small town where my grandmother lives the population is both black and white but the two Baptist churches, next door to each other, are segregated by race. I asked my grandma why that was and she said "we're not welcome over there" -- I asked a white woman I know in the area who I used to sew for why, and she said I was "stirring up trouble." But, all of the people in these churches are very old. I don't know where the other young people are... or if they even go to church.
Integration should not mean a death to the unique cultural traditions of black churches. In some cases formerly all white congratulations have a few black members, in other cases black churches have accepted a few white members. It is easiest when the new members are married to existing member of the church, but some tension can develop when, for example a neighborhood is being gentrified, and it is still the case that the members of some white congratulations make black members feel uncomfortable leading them to leave after a few Sundays. I like to imagine that in 50 or 100 years things will be more integrated-- and will still have the echos of the old institutions and styles, but it won't look as segregated as it does today. But, maybe that it just wishful thinking.