Atheism is the theory that there is no God. Now one kind is a theoretical kind, where someone just sits down and starts thinking about it, and they come to a conclusion that there is no God. The other kind is a practical atheism, and that kind goes out of living as if there is no God. And you know there are a lot of people who affirm the existence of God with their lips, and they deny his existence with their lives. You’ve seen these people who have a high blood pressure of creeds and an anemia of deeds.

Martin Luther King, Jr. (1929-1968) American clergyman, civil rights leader, social activist, preacher

“The Three Dimensions of a Complete Life,” sermon, New Covenant Baptist Church, Chicago (9 Apr 1967)
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See also here.