In the nonreligious vernacular, the word “ecumenical” means “general in extent or influence.” It's rarely a good idea to be fetishistic over the etymology or even the present meaning of terms, but in this instance the definition lands right on the mark. In short, ecumenism is the antidote to what comes off as narrow, and even dogmatic, sectarianism.

As a priest in the Church of England and later the Archbishop of Canterbury, William Temple (1881–1944) proclaimed, “The ecumenical movement is the great new fact of our era.” What was it that excited him so? The promise of the movement was that after centuries of separation and hostility, Christians had begun to capture “the simple biblical truth that the church of the people of God and the body of Christ must exemplify in the world how God gathers people together from the ends of the earth to live as a new humanity.” Cooperation, not separation, was the operative concept.

These words were not idle; the ideal of unity bore fruit. In time, churches representing over 1.5 billion members are now engaged with one another in councils of churches, theological dialogues, various forms of collaborative missions, common prayers, and other expressions of ecumenical life.