Institutional religion, especially churches, are rapidly declining in America and there is no lack for explanations from all sides -religious and secular explanations.
Yet, any explanation for why religions are declining must also be able to explain why virtually every secular social institution, like the boy scouts, the free masons, and the NAACP, are also declining in membership.
It's not just churches, people just don't know how to be a part of a community anymore.
The NAACP I can't speak to. I'm white. I would ask the Black community.
And my reasoning makes much more sense than some sort of amorphous "malaise." Communities, what they mean, who gets to be a part of them, and where they even exist have changed ENORMOUSLY in the last fifty years. Not a lot of organizations have reflected that, to my mind.
@Dseitz I don't follow your argument. (This is not a critique of the argument per se, I just actually don't understand what you mean.)