His involvement in Demme's documentary led to an unlikely career as an actor in more than a dozen films over the next two decades, including roles in Philadelphia, The Addiction, Beloved, and Rachel Getting Married.
[1] During that time, Castle became very involved with the American civil rights movement, including traveling to Mississippi to march with Martin Luther King Jr.[1] He became one of the city's most vocal activists.
An opponent of the Vietnam War, he allowed 1960s left-wing groups, including the Black Panthers and Students for a Democratic Society, to use both his home and St. John's Episcopal Church for their meetings.
[1] Castle was also the football coach for several years at North Country Union High School where he led the team, with his son John at quarterback, to the state championship game in 1981.
[citation needed] Castle next became the rector of St. Mary's Episcopal Church, located on West 126th Street in Manhattan's Harlem neighborhood.
In the early 1990s, he protested against the much larger Cathedral of St. John the Divine, also an Episcopal church, for honoring retired General Colin Powell and other leading figures in Operation Desert Storm.