Quoting Theology: Martin Luther King Jr.

"A religion true to its nature must also be concerned about man's social conditions. Religion deals with both earth and heaven, both time and eternity. Religion operates not only on the vertical plane but also on the horizontal. It seeks not only to integrate men with God, but to integrate men with men and each man with himself. This means, at bottom, that the Christian gospel is a two-way road. On the one hand, it seeks to change the souls of men and thereby unite them with God; on the other hand, it seeks to change the environmental conditions of men so that the soul will have a chance after it is changed. Any religion that professes to be concerned with the souls of men and is not concerned with the slums that damn them, the economic conditions that strangle them, and the social conditions that cripple them is a dry-as-dust religion. Such a religion is the kind the Marxists like to see--an opiate of the people."

-Martin Luther King Jr.