What did MLK say about the role of the church?

The role of the church was one of the subjects nearest to my heart, and I returned to it again and again throughout my ministry — with love, but also with honest disappointment. The clearest way I can put it is this: the church must be neither servant nor master of the state, but its conscience. In The Strength to Love, I wrote that “The church must be reminded that it is not the master or the servant of the state, but rather the conscience of the state”. That is the calling. And when the church abandons it, it becomes something worse than irrelevant — it becomes complicit. In my Letter from Birmingham City Jail, I described what that abandonment looks like in practice. I had looked at the South's beautiful churches with their lofty spires and found myself asking: who is their God? Because “The contemporary church is often a weak, ineffectual voice with an uncertain sound. It is so often the arch-supporter of the status quo”. The early Christians, by contrast, were thermostats — they transformed the moral temperature of society. The church today too often only records it, like a thermometer. I also insisted the church must put its own house in order first. As I wrote in Stride Toward Freedom, “It is appalling that the most segregated hour of Christian America is eleven o’clock on Sunday morning”. You cannot speak prophetically to the world while practicing injustice within your own walls.