— Martin Luther King, Jr. American clergyman, activist, and leader in the American Civil Rights Movement 1929 - 1968
Context: "The apparent apathy of the Negro ministers presented a special problem. A faithful few had always shown a deep concern for social problems, but too many had remained aloof from the area of social responsibility. Much of this indifference, it is true, stemmed from a sincere feeling that ministers were not supposed to get mixed up in such earthly, temporal matters as social and economic improvement; they were to "preach the gospel" and keep men's minds centered on "the heavenly." But however sincere, this view of religion, I felt, was too confined.
Certainly, otherworldly concerns have a deep and significant place in all religions worthy of the name. Any religion that is completely earthbound sells its birthright for a mess of naturalistic pottage. Religion at its best, deals not only with man's preliminary concerns but with his inescapable ultimate concern. When religion overlooks this basic fact it is reduced to a mere ethical system in which eternity is absorbed into time and God is relegated to a sort of meaningless figment of the human imagination. But 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 seek to change the environmental conditions of men so that 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.
Stride Toward Freedom (1958), pp. 28-29<!-- New York: Ballantine Books, -->