From 1963 to 1964, he served as Rector of Christ Church in Corning, New York, participating in the 1963 March on Washington for Jobs and Freedom, where Martin Luther King Jr. gave his famous "I Have a Dream" speech.
From 1966 to 1972 he was director of the Continuing Education Department at Virginia Seminary, also serving, in 1969, as priest-in-charge at St. Alban's Church in Tokyo, Japan, and studied systematic theology at The Catholic University of America, Washington, D.C. (1969-1971).
Among the issues receiving his support and leadership were racial integration of the public schools, revision of the Episcopal prayer book, the ordination of women, and, ultimately, the acceptance of homosexuals in the church.
Sims married a second time on August 27, 1988, to Mary Page Welborn, and together they moved the Institute for Servant Leadership to Hendersonville, North Carolina.
Sims is the author of five books: Invitation to Hope: A Testimony of Encouragement (1974); Purple Ink: A Selection of the Writings of Bennett J. Sims as Bishop of Atlanta (1982); Servanthood: Leadership for the Third Millennium (1997); Why Bush Must Go: A Bishop’s Faith-Based Challenge (2004); and The Time of My Life: A Spiritual Pilgrimage Grounded in Hope (2006).