The Rev. Robert S. Graetz was 27, recently ordained in the Lutheran church, when he received his first full-time assignment. It was 1955, and with a shortage of African American ministers, Lutheran officials decided to send the White clergyman to a predominantly Black church in Montgomery, Ala.

Rev. Graetz had demonstrated a growing interest in civil rights, joining the NAACP while in college and preaching to a small, majority-Black congregation in Los Angeles as an intern. Before sending him to Alabama, church elders asked him to promise not to “start any trouble.”

Years later, after Rev. Graetz had become the only White minister to participate in the Montgomery bus boycott and long after he had confronted death threats and bombs from Ku Klux Klan members who targeted his home, he still believed he had kept his promise.

“We did not start that trouble,” he often said. “We joined the trouble.”

Rev. Graetz, who devoted his ministry to battling poverty and discrimination and to building what his colleague the Rev. Martin Luther King Jr. called “the Beloved Community,” was 92 when he died Sept. 20 at his home in Montgomery. He had Parkinson’s disease, said his wife, Jeannie Ellis Graetz.

From its earliest days in December 1955, the Montgomery bus boycott marked a turning point in what was increasingly recognized as a national civil rights movement. Rosa Parks’s refusal to give up her bus seat to a White man, in defiance of a city ordinance and state law, sparked a protest that lasted 381 days, turning Parks into a founding symbol of the struggle and establishing King as the movement’s charismatic young leader.

It also transformed Rev. Graetz into a symbol of White support for Blacks in Montgomery and into a target for Klansmen and other white supremacists. Segregationists found the idea of a White man’s actively cooperating with the boycott “astonishing and outrageous,” according to civil rights historian J. Mills Thornton III’s book “Dividing Lines” (2002), and twice bombed his parsonage.

Rev. Graetz was “the only White visibly active in the protest,” said David J. Garrow, another civil rights historian, and was the only White person to serve on the board of the Montgomery Improvement Association, the Black community group formed to coordinate the boycott.

He had met King, the association’s president, soon after arriving in Montgomery. “I decided that anybody who sounded as smart as he was and was articulate as he was, and had the name Martin Luther, I had to get to know him better,” Rev. Graetz told a public television interviewer in 2011.

And he was a friend and neighbor of Parks, a seamstress who led an NAACP youth group that met at his church, Trinity Lutheran Evangelical. When he learned secondhand that someone had been arrested for refusing to give up a seat on a bus, he called Parks to inquire, not realizing it was her.

“A wonderful lady, quiet, dignified, respectful,” he later told NPR, “and yet full of that kind of quiet courage that you rarely see in anybody.”

On the Sunday after her arrest, Rev. Graetz stood at the pulpit and advised the more than 200 members of his congregation to participate in the newly announced bus boycott, adding, “If you need a ride, I’ll be glad to come and take you wherever you need to go.”

Rev. Graetz joined the boycott’s organizers in driving some of Montgomery’s 40,000 Black residents to and from work each day and helped oversee fundraising efforts to support the makeshift taxi service. He also sought to enlist other White ministers in the cause, asking them in a letter to “consider this matter prayerfully and carefully, with Christian love.”

None heeded his call. Still, in the 1958 memoir “Stride Toward Freedom,” King called Rev. Graetz “a constant reminder to us in the trying months of the protest that many white people as well as Negroes were applying the ‘love-thy-neighbor-as-thyself’ teachings of Christianity in their daily lives.”

The boycott organizers met frequently, including over coffee at 2:30 in the morning, and bonded as they and their families confronted threatening letters and phone calls. Vandals threw rocks through Rev. Graetz’s windows and poured sugar into his car’s fuel tank. His tires were slashed, and he said that he was sometimes followed when he drove out of Montgomery, leading him to never use the same route twice in a row.

In August 1956, a few sticks of dynamite exploded about 40 feet from his front door, doing minimal damage. Rev. Graetz and his family were out of town, attending a civil rights workshop with Parks at the Highlander Folk School in Tennessee. Montgomery Mayor W.A. Gayle dismissed the attack, asserting that it might have been “a publicity stunt to build up interest of the Negroes in their campaign.”

Five months later, a second bomb went off late at night, when the Graetzes were home with their 9-day-old son. Their front door and front windows were shattered, and the roof was raised several inches, Rev. Graetz wrote in a 2006 memoir, “A White Preacher’s Message on Race and Reconciliation.”

After “stumbling over something in the driveway,” he added, he and his neighbors realized that another, unexploded device had landed outside the house, with enough dynamite to level the neighborhood. That same night, assailants bombed four Black churches and the home of the Rev. Ralph D. Abernathy, another boycott leader. (Seven Klansmen were arrested, but no one was ever convicted in connection with the bombings.)

Fred D. Gray, a civil rights lawyer who defended Parks, later wrote that when Rev. Graetz was attacked in the bombing, “there appeared to be even more hostility toward him — if it was possible — than toward Dr. King,” presumably because Rev. Graetz was White.

In part, the hostility was driven by a sense of defeat. The Supreme Court had outlawed bus segregation in November 1956, and the court order went into effect in Montgomery the next month, spurring an end to the boycott.

The night the court decision was announced, Rev. Graetz read from the Bible at a mass meeting, choosing a passage from Paul’s letter to the Corinthians: “When I was a child, I spoke as a child, I understood as a child, I thought as a child; but when I became a man, I put away childish things.”

“The congregation burst into applause,” King recalled in his memoir. “Soon they were shouting and cheering and waving their handkerchiefs, as if to say that they knew they had come of age, had won new dignity.” After a second outburst occurred at the end of Rev. Graetz’s reading, King realized that something had changed: “I knew then that non­violence, for all its difficulties, had won its way into our hearts.”

Robert Sylvester Graetz Jr. was born in Clarksburg, W.Va., on May 16, 1928, and grew up in the state capital, Charleston. His father was a glass-company engineer, his mother a homemaker, and the family was filled with Lutheran preachers, leading Rev. Graetz to join the ministry.

He received a bachelor’s degree in 1950 from Capital University, a Lutheran school outside Columbus, Ohio, where he was doing research on anti-Semitism when he began to learn the history of anti-Black discrimination. “I in my Whiteness didn’t know anything about it,” he later said. “It was as if I had discovered a new country.”

Rev. Graetz graduated from the Evangelical Lutheran Theological Seminary (now Trinity Lutheran Seminary) in Columbus and returned to preach in the city in 1958. He spent most of his career as a minister in Ohio, aside from several years in the late 1960s when he worked in Washington, helping organize a Lutheran street ministry and handing out food in the aftermath of the 1968 riots ignited by the assassination of King.

“The riots were part of that mourning process,” he wrote in his memoir.

Rev. Graetz was effectively joined in his ministry by his wife, the former Jean Ellis, whom he married in 1951. They had seven children, including Robert S. Graetz III, who inspired his parents to join the gay rights movement before his death in 1991 after being diagnosed with AIDS.

In addition to his wife and six remaining children, Rev. Graetz is survived by a sister, 26 grandchildren, 17 great-grandchildren, and one great-great-grandson.

In a phone interview, his wife, now 90, recalled their years in Montgomery with some fondness. “The Ku Klux Klan didn’t like us, but we got along with everybody else,” she said. “We joked that we had the only integrated swimming pool in Alabama: a big tractor tire in the backyard. Put a tarp in it and fill it with water, and little kids had a good time in there.”

She said the memory of the bombing, though, was still raw. Along with her husband, she had learned “that forgiveness is necessary when you’re going through all this.”

“When you have hate in your heart, it’s like a cancer in your life,” she added. “One of our jobs in life is to heal all the bad things that are going on and help people to realize that fairness is necessary.”