The Rev. James Lawson Jr., an apostle of nonviolent protest who schooled activists to withstand brutal reactions from white authorities as the Civil Rights Movement gained traction, has died, his family said Monday. He was 95.

His family said Monday that Lawson died on Sunday after a short illness in Los Angeles, where he spent decades working as a pastor, labor movement organizer and university professor.

Lawson was a close adviser to the Rev. Martin Luther King Jr., who called him “the leading theorist and strategist of nonviolence in the world.”

Lawson met King in 1957, after spending three years in India soaking up knowledge about Mohandas K. Ghandi’s independence movement. King would travel to India himself two years later, but at the time, he had only read about Ghandi in books.

The two Black pastors — both 28 years old — quickly bonded over their enthusiasm for the Indian leader’s ideas, and King urged Lawson to put them into action in the American South.

Lawson soon led workshops in church basements in Nashville, Tennessee, that prepared John Lewis, Diane Nash, Bernard Lafayette, Marion Barry, the Freedom Riders and many others to peacefully withstand vicious responses to their challenges of racist laws and policies.

Lawson’s lessons led Nashville to become the first major city in the South to desegregate its downtown, on May 10, 1960, after hundreds of well-organized students staged lunch-counter sit-ins and boycotts of discriminatory businesses.

Lawson’s particular contribution was to introduce Ghandian principles to people more familiar with biblical teachings, showing how direct action could expose the immorality and fragility of racist white power structures.

Ghandi said “that we persons have the power to resist the racism in our own lives and souls,” Lawson told the AP. “We have the power to make choices and to say no to that wrong. That’s also Jesus.”

Years later, in 1968, it was Lawson who organized the sanitation workers strike that fatefully drew King to Memphis. Lawson said he was at first paralyzed and forever saddened by King’s assassination.

“I thought I would not live beyond 40, myself,” Lawson said. “The imminence of death was a part of the discipline we lived with, but no one as much as King.”

Still, Lawson made it his life’s mission to preach the power of nonviolent direct action.

“I’m still anxious and frustrated,” Lawson said as he marked the 50th anniversary of King’s death with a march in Memphis. “The task is unfinished.”

James Morris Lawson Jr., was born on Sept. 22, 1928, the son and grandson of ministers, and grew up in Massillon, Ohio, where he became ordained himself as a high school senior.

He told The Tennessean that his commitment to nonviolence began in elementary school, when he told his mother that he had slapped a boy who had used a racial slur against him.

“What good did that do, Jimmy?” his mother asked.

That simple question forever changed his life, Lawson said. He became a pacifist, refusing to serve when drafted for the Korean War, and spent a year in prison as a conscientious objector. The Fellowship of Reconciliation, a pacifist group, sponsored his trip to India after he finished a sociology degree.

Gandhi had been assassinated by then, but Lawson met people who had worked with him and explained Ghandi’s concept of “satyagraha,” a relentless pursuit of Truth, which encouraged Indians to peacefully reject British rule. Lawson then saw how the Christian concept of turning the other cheek could be applied in collective actions to challenge morally indefensible laws.

Lawson was a divinity student at Oberlin College in Ohio when King spoke on campus about the Montgomery bus boycott. King told him, “You can’t wait, you need to come on South now,’” Lawson recalled in an Associated Press interview.

Lawson soon enrolled in theology classes at Vanderbilt University, while leading younger activists through mock protests in which they practiced taking insults without reacting.

The technique swiftly proved its power at lunch counters and movie theaters in Nashville, where on May 10, 1960, businesses agreed to take down the “No Colored” signs that enforced white supremacy.

“It was the first major successful campaign to pull the signs down,” and it created a template for the sit-ins that began spreading across the South, Lawson said.

Lawson was called on to organize what became the Student Nonviolent Coordinating Committee, which sought to organize the spontaneous efforts of tens of thousands of students who began challenging Jim Crow laws across the South.

Angry segregationists got Lawson expelled from Vanderbilt, but he said he never harbored hard feelings about the university, where he returned as a distinguished visiting professor in 2006, and eventually donated a significant portion of his papers.

Lawson earned that theology degree at Boston University and became a Methodist pastor in Memphis, where his wife Dorothy Wood Lawson worked as an NAACP organizer. They moved several years later to Los Angeles, where Lawson led the Holman United Methodist Church and taught at California State University, Northridge and the University of California. They raised three sons, John, Morris and Seth.

Lawson remained active into his 90s, urging younger generations to leverage their power. Eulogizing the late Rep. John Lewis last year, he recalled how the young man he trained in Nashville grew lonely marches into multitudes, paving the way for major civil rights legislation.

“If we would honor and celebrate John Lewis’ life, let us then re-commit our souls, our hearts, our minds, our bodies and our strength to the continuing journey to dismantle the wrong in our midst,” Lawson said.