Since its founding in 1930 as a Gothic cathedral built by John D. Rockefeller, Riverside Church has espoused a progressive and often pacifist agenda. But internal fights have plagued the congregation for more than a decade.

Longtime members ascribe some of the tension to changes in the racial makeup of the 2,700-member congregation, which was once about 60 percent white and 40 percent black, and now is roughly the reverse. Some of the troubles are traced to generational differences, between older whites with roots in the civil rights era and younger, middle-class black members who are less politicized. ...