AUDIE CORNISH, HOST:
Donald Trump, Hillary Clinton, Michael Flynn, Jeff Sessions - you already know the names of the key figures in James Comey's book but maybe not this name...
MARY LOUISE KELLY, HOST:
CORNISH: ...Reinhold Niebuhr, a man who's been dead since 1971.
KELLY: Niebuhr was a liberal Protestant theologian, the most prominent one of his time.
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MIKE WALLACE: If religion is good, why should our society be based upon a separation between the church and the state?
REINHOLD NIEBUHR: Your if is a very big one. If religion is good, it may be very good, and it may be bad.
KELLY: That's Niebuhr himself speaking with journalist Mike Wallace in 1958.
CORNISH: Niebuhr was a leading voice for many on the religious left.
KELLY: And he has a big admirer in James Comey, whose new book opens with one of his quotes.
CORNISH: Man's capacity for justice makes democracy possible, but man's inclination to injustice makes democracy necessary.
KELLY: Niebuhr's writings pushed Protestant Christians to work towards social justice. Here's his daughter, Elisabeth Sifton, on Fresh Air in 2005.
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ELISABETH SIFTON: He wrote somewhere that rich princes always imagine that they are wise. They imagine that they think they're wise because they're powerful and at the top of the heap, and it never occurs to them that they're only there because they're - they have all the money, not because they are wiser than anyone else. So he inveighed constantly against the powers that be that he felt were unjust and indifferent to suffering.
CORNISH: Niebuhr was the subject of James Comey's undergraduate thesis.
KELLY: And Reinhold Niebuhr was also Comey's Twitter nom de plume for a while.
CORNISH: Comey's book explains how he first discovered the theologian. We had a colleague read from that section.
UNIDENTIFIED PERSON: (Reading) One day, I was headed to a chem lab and noticed the word death on a bulletin board. I stopped. It was an advertisement for a class in the religion department. I took the course, and everything changed.
KELLY: Perhaps the best known piece of Niebuhr's writing is this, a prayer he wrote in 1943.
CORNISH: God grant me the serenity to accept the things I cannot change, courage to change the things I can and wisdom to know the difference.
KELLY: A bit of writing recognized today as the Serenity Prayer. Transcript provided by NPR, Copyright NPR.