Cone, however, said neither Niebuhr nor any other famous white pastor at the time spoke out against the most brutal manifestation of white racism in the 20th century America: lynching.

Between 1880 and 1940, Cone says, an estimated 5,000 black men and women were lynched. Their murders were often treated as festive affairs. Women and children cut off the ears of lynching victims as souvenirs. People mailed postcards of lynchings. One postcard of a charred lynching victim read, "This is the barbeque we had last night."

But Niebuhr said nothing about lynching, little about segregation, and once turned down King's request to sign a petition calling on the president to protect black children integrating Southern schools, Cone said.

Niebuhr's decision not to speak out against lynching encouraged other white theologians and ministers to follow suit, Cone said, because Niebuhr was considered the nation's greatest theologian.

"White theologians didn't say anything about lynching," Cone said from his office at Union Theological Seminary in New York, where he teaches a course on Niebuhr. "I tried to find a white theologian who addressed it in a sustained way. No one did it."

Cone's criticism of Niebuhr baffles at least one well-known Niebuhr scholar. Charles Lemert, author of "Why Niebuhr Matters," said King often cited Niebuhr as an inspiration. He said he'd never heard that Niebuhr rejected a petition request from King. "It would be so remote from everything the man was."

Lemert said Niebuhr had established a long record of speaking out against racism, beginning when he became a pastor in Detroit. Niebuhr may not have spoken out against lynching and other forms of racism later on because of another reason, Lemert said.

"He had a debilitating stroke in 1951," Lemert said. "By the time the civil rights movement was full blown, he was retired and getting ill."

Why Cone is angry

Cone has spent much of his career condemning the white church for saying little about slavery or racial justice. Yet his pugnacious reputation doesn't jibe with his appearance. He is a slight man with a boyish face, cinnamon complexion and dimples. He has a high-pitched voice that drips with the Southern inflections of his native Arkansas.