America was Methodist, once upon a time—or Baptist, or Presbyterian, or Congregationalist, or Episcopalian. Protestant, in other words. What can we call it today? Those churches simply don’t mean much any more. That’s a fact of some theological significance. It’s a fact of genuine sorrow, for that matter, as the aging members of the old denominations watch their congregations dwindle away: funeral after funeral, with far too few weddings and baptisms in between. But future historians, telling the story of our age, will begin with the public effect in the United States.
As he prepared to leave the presidency in 1796, George Washington famously warned, “Whatever may be conceded to the influence of refined education on minds of peculiar structure, reason and experience both forbid us to expect that national morality can prevail in exclusion of religious principle.” Generally speaking, however, Americans tended not to worry much about the philosophical question of religion and nation. The whole theologico-political problem, which obsessed European philosophers, was gnawed at in the United States most by those who were least churched.
We all have to worry about it, now. Without the political theory that depended on the existence of the Protestant Mainline, what does it mean to support the nation? What does it mean to criticize it? The American experiment has always needed what Alexis de Tocqueville called the undivided current, and now that current has finally run dry.
http://www.firstthings.com/article/2008/08/001-the-death-of-protestant-america-a-political-theory-of-the-protestant-mainline
