Since the Revolutionary War, Mainline Christianity has been comprised of the Seven Sisters of American Protestantism--the Congregational Church, the Episcopal Church, the Evangelical Lutheran Church, the Presbyterian Church, the United Methodist Church, the American Baptist Convention, and the Disciples of Christ.

These denominations have been the dominant cultural representatives since the nineteenth century of how and where the majority of American Christians worship. Today, however, the Seven Sisters no longer represent most American Christians. The Mainline has been shrinking...