Faith communities in which people worship together are arguably the single most important repository of social capital in America

Faith communities in which people worship together are arguably the single most important repository of social capital in America. "The church is people," says Reverend Craig McMullen, the activist co-pastor of the Donchester Temple Baptist Church in Boston. "It's not a building; it's not an institution, even. It is relationships between one person and the next." As a rough rule of thumb, our evidence shows, nearly half of all associational memberships in America are church related, half of all personal philanthropy is religious in character, and half of all volunteering occurs in a religious context.

D. Putnam, Bowling Alone (2000), 66

I thin this really sums up the two sided nature of US religiosity. It is their dominant vehicle for cohesion, but it's do resistant to institutionalisation that it can easily just go off the rails.