It was March 3, 1968, and America’s most influential pastor, the preeminent leader of the civil rights movement, was in the pulpit of Atlanta’s Ebenezer Bapist Church. His theme that Sunday was the neverending tension between good and evil — a tension that exists not merely in the abstract, not just “out somewhere” in the “forces of the universe,” but in the heart of every human being.

Including his own.

“You don’t need to go out this morning saying that Martin Luther King is a saint. Oh, no,” he exhorted the congregation. “I want you to know this morning that I’m a sinner like all of God’s children. But I want to be a good man.”

He spoke of the constant struggle to resist base impulses. “Every time you set out to be good, there’s something pulling on you, telling you to be evil,” King preached. “There is a schizophrenia … within all of us. And there are times that all of us know somehow that there is a Mr. Hyde and a Dr. Jekyll in us.”

MLK’s flock that morning didn’t know just how sinful their shepherd could be. But the lurid details have long since been made public. Many first came out during the 1975 Church Committee hearings, a Senate investigation into abuses by US intelligence agencies. Those hearings exposed the obsessive quest for dirt on King by the FBI, which was authorized by Attorney General Robert Kennedy to tap the civil rights leader’s phones and bug his hotel rooms. The bureau compiled salacious reports on King’s sexual activity, peddling some of the information to reporters and politicians.

The FBI’s quest to discredit King is one of the most shameful chapters in its history. But there is no denying King’s seamier side. He was a compulsive philanderer, who cheated on his wife Coretta with numerous mistresses, including two in the Lorraine Motel in Memphis the night before his assassination. “We all understood and believed in the biblical prohibition against sex outside of marriage,” King’s devoted friend and fellow pastor, Ralph Abernathy, wrote in The Walls Came Tumbling Down, his 1989 memoir. “It was just that he had a particularly difficult time with that temptation.”

Now this unpleasant topic is back in the news. In a long essay for the British magazine Standpoint, the respected historian David Garrow sheds new light on King’s womanizing. Garrow — author of a Pulitzer-winning biography of MLK and a noted authority on the civil rights movement — quotes from newly released FBI surveillance summaries that “expose in graphic detail the intense focus on King’s extensive extramarital sexual relationships with dozens of women.” The most disturbing describes King’s “presence in a Washington hotel room when a friend, a Baptist minister, allegedly raped one of his ‘parishioners,’ while King ‘looked on, laughed, and offered advice.’”

The actual FBI tape of that episode still exists in a National Archives vault, and could presumably confirm or refute the FBI’s shocking claim. But all of the MLK transcripts and recordings were put off limits for 50 years by federal court order in 1977, and won’t become available to researchers until January 31, 2027. “When they are made fully available,” writes Garrow, “a painful historical reckoning concerning King’s personal conduct seems inevitable.”

A number of Garrow’s fellow scholars have squared off over his essay. Some suggest that it needlessly sensationalized allegations that may not be reliable; others argue that Garrow was professionally obliged to incorporate the new material into the record. Of course the debates over King and his legacy will go on, just as the debates over other historical giants go on. The treatment of women looms larger today as an element in assessing reputation than it did a generation ago; in a #MeToo environment, the disclosures of MLK’s sexual dissipation are bound to affect the way historians judge him.

What will not change is King’s status as one of the towering moral champions of the 20th century.

A flawed man he may have been, as he told his parishioners in Atlanta that day, but MLK was also a figure of almost inconceivable moral valor. He devoted his life to the worthiest goal in American history — the goal of racial fairness and freedom, of an end to oppression based on color, of a nation committed to the God-given equality of all its citizens.

King, the 1964 Nobel laureate for peace and a singular advocate of nonviolent civil disobedience, never wavered from his absolute commitment to peaceful change. He was repeatedly targeted by enemies wielding knives, guns, and dynamite — he had a premonition that he would be assassinated — yet he steadfastly rejected violence. He deployed his extraordinary power as a speaker not to enrage or mock, but to elevate and ennoble. His 1963 “I Have a Dream” speech ranks with Lincoln’s Gettysburg Address and Patrick Henry’s “Give Me Liberty or Give Me Death” as some of the most indelible and affecting rhetoric in American history.

Like everyone who has ever lived, MLK had his ignoble side. He should have been a better man, a better husband, a better Christian. For all that, he was one of the greatest Americans who ever lived, and a hero for the ages.