King initially came to national prominence leading the bus boycott in Montgomery, where he was serving his first job as a local pastor.
Working closely with him was a young white pastor, the Rev. Robert Graetz.
"We were here because God brought us here," Graetz told the PBS program Religion & Ethics NewsWeekly. "And in a very real sense this changed the character of the movement because it was not totally black then from that point on."
Graetz, now 82, still works with his wife in Montgomery for civil rights, reconciliation and a vision that began more than 50 years ago -- a vision they shared with King called "the beloved community."
"We are all different, but we are still all together in this one relationship," Graetz said, "and the key to that kind of relationship was respect."
Graetz grew up in an all-white Lutheran community in West Virginia.
As a college student in Ohio, he experienced what he called his "race relations awakening." He and his wife Jean got involved in ministries in black communities, and when he finished seminary, Lutheran officials asked him to pastor an all-black congregation in Montgomery.
"We had very few black pastors because we required seminary training for all pastors," Graetz said. "That's why they needed some white pastors like me to serve in largely black congregations."
The young family arrived in Montgomery in 1955 and began their work at Trinity Lutheran Church. One of the first people they met was a neighbor named Rosa Parks, an adult adviser to an NAACP youth group that met at their church.
Graetz was also introduced to another new pastor in town, King, who had arrived the year before.
"I decided," Graetz said laughing, "that anybody who sounded as smart as he was, and was as articulate as he was, and had the name Martin Luther, I had to get to know him better."
He also came to know the struggles of his congregation because of legalized segregation, including on the city bus system. Several local activists had been talking about a boycott, and when Parks was arrested for refusing to give up her seat to a white man, the stage was set for a showdown.
Initially, Graetz was conflicted on joining, unsure what church hierarchs might think.
"Jeannie and I prayed about that a lot and finally decided the only way that I could continue to be the pastor here was to take part in the activities that our members were taking part in," he said, "and from that point we were totally a part of what was happening."
The Sunday before the boycott began, Graetz stood before his congregation and voiced his full support. As the boycott began, he spent the whole day driving people around.
Janice Franklin, director of the National Center for the Study of Civil Rights & African-American Culture, said Graetz was King's confidante and instrumental in carpooling so that everyone "would have an opportunity to stand up for what was right in the Montgomery bus boycott."
Graetz said it was exhilarating to be a part of it all.
"The feeling among the people across the community was that we were doing something that was changing the world," he said.
Howard Robinson, an archivist at Alabama State University, said the Graetzs were "one of the very few white people in Montgomery who took a very overt, obvious position in support of the boycott. And they suffered because of it."
The family became targets of the Ku Klux Klan.
"I was scared to take the trash out because I knew that these people had been around our house and had put sugar in the gas tank and slashed our tires and I didn't feel safe outside at night," Jean Graetz said.
Their parsonage was bombed twice -- once when no one was home, and once in the middle of the night when everyone was sleeping. The house sustained some damage but no one was injured.
Jean Graetz said African-American friends and sympathetic white supporters gave them strength.
"I felt that the Lord had put a circle of love around us because we had wonderful friends, and I knew God's love was around us and I just pictured this, this circle around us so that the hate from the people couldn't get through," she said.
The couple remains active in civil rights causes and as consultants at the ASU center. They lead discussions about justice and the work that still needs to be done in order to achieve their vision of the beloved community.
"People will say to us, `You know, we really appreciate what you did,' and our response always is, `It wasn't just us, it was 50,000 black people who stood together, who walked together, who worked together, who stood up against oppression.
"If it had had not been for this whole body of people working together," he said, "this would not have happened."