It was from the pulpit of the Riverside Church that Martin Luther King, Jr., first publicly voiced his opposition to the Vietnam War, that Nelson Mandela addressed U.S. church leaders after his release from prison, and that speakers as diverse as Cesar Chavez, Jesse Jackson, Desmond Tutu, Fidel Castro, and Reinhold Niebuhr lectured church and nation about issues of the day. The greatest of American preachers have served as senior minister, including Harry Emerson Fosdick, Robert J. McCracken,...