Splinter Churches Realign Mainline Protestantism

The question now is whether these breakaway groups signal a seismic shift in American Protestantism, or just a few fissures in the theological terrain.

In some ways, the rifts are nothing new. American Protestants have been splintering since Roger Williams left Plymouth Colony in the 1630s, said Nancy Ammerman, a sociologist of religion at Boston University.

Yet the schisms counter a 20th-century trend in which ethnic and regional Protestant groups merged to form big-tent denominations such as the ELCA and PC(USA). 

"What we may be experiencing at this point is the limit of that movement to draw a lot of diversity under one umbrella," said Ammerman, author of Pillars of Faith: American Congregations and Their Partners.