Burt died after a long illness, said his daughter Susan Burt.
A friend of the Rev. Martin Luther King Jr., Burt helped organize massive civil rights rallies in Los Angeles, including a 1963 event in South Los Angeles that attracted 30,000 people. He also was a vocal supporter of Cesar Chavez and the farmworkers movement.
Burt was one of four rectors "who really shaped All Saints to be a peace and justice church," said Rector J. Edwin Bacon, who currently leads the Pasadena church, one of Southern California's largest and most liberal.
It is known for its outspoken clergy and the strong stands it has taken against war, poverty and racial and ethnic discrimination over the last seven decades, beginning in 1942 when Rector Frank Scott stood in front of trains to protest the removal of Japanese Americans to internment camps during World War II.
Burt, who succeeded Scott in 1957, became known over the next decade for his courageous support of King.
In 1963, Burt sat in the first row behind the lectern at South L.A.'s Wrigley Field (later demolished), where King addressed what was then the largest civil rights rally held in the city. It raised thousands of dollars to support King's nonviolent crusade against racial inequality in the South, including a $20,000 pledge by entertainer Sammy Davis Jr., one of several celebrities who spoke at the rally.
In 1964, he again sat behind King as the great civil rights leader addressed 15,000 people at the Coliseum for an interfaith rally called "Religious Witness for Human Dignity."
His vocal backing of King caused some worshipers to leave All Saints; an anonymous caller threatened to bomb Burt's house. When a group of church trustees asked him to stop preaching about racial issues, "he said he was always open for people to come and share their dissent with him, but the pulpit at All Saints is free," said George F. Regas, who succeeded him as rector.
He believed that so strongly that he "felt obligated the next Sunday to preach on racial justice," Regas noted.
Burt was born April 11, 1918, in Marquette, where his father, Bates Burt, was a community activist and rector of St. Paul's Episcopal Church. John's younger brother, Alfred S. Burt, became a famous composer of Christmas carols, including "Caroling Caroling" and "Some Children See Him."
John Burt graduated from Amherst College in 1940. After postgraduate studies at Columbia University and a stint as a social worker on New York's Lower East Side, he entered the Episcopal Theological Seminary in Virginia and was ordained in 1943.
During World War II he served as a Navy chaplain in the Pacific theater. After the war, he served at St. John's Episcopal Church in Youngstown, Ohio, where he helped lead efforts to integrate swimming pools and housing.
In 1957, he arrived at All Saints in Pasadena, where he was active in civic matters as president of the Pasadena Community Planning Council. He also was president of the Southern California Council of Churches and vice chairman of the United Nations Assn. of Southern California.
In 1967, he became the eighth bishop of Ohio. An early advocate for the ordination of women, he vowed to resign as bishop if the Episcopal General Convention failed to approve the ordination of female priests in 1976. The measure succeeded, and in early 1977, Burt ordained the first of eight women he would elevate to the priesthood during his 17-year tenure as bishop.
In 1978, he helped found a coalition of ecumenical and political leaders to keep steel plants open in Youngstown, with proposals that included allowing workers to buy the mills. The effort failed, but his advocacy earned him the prestigious Thomas Merton Award, which had previously been given to activists Dorothy Day, Joan Baez and Dick Gregory.
After retiring in 1984, Burt remained active in the ecumenical movement as president of the National Christian Leadership Conference for Israel from 1992 to 1998.
He is survived by his wife, Martha; four daughters; six grandchildren and five great-grandchildren.