Another helpful article

E.J. Dionne has an article called "Faith and Politics after the Religious Right" in the latest Commonweal magazine. It gives a helpful overview, I think, of 3 major phases in the history of religion's role in American public life. In brief (his nuances are well worth looking at), the first phase was Protestant hegemony (founding to JFK), the second was the phase of a pluralism that turned into secularism, and the third phase (current) is the push back (and, actually, debate over) against the marginalization of faith in public life.

Dionne gives a very helpful example to illustrate the difference between stages 2 and 3:

The clearest symbol of the difference between the second and third stages is the sharp contrast between the way John F. Kennedy treated his faith as a public issue in the 1960 presidential campaign and how Joe Lieberman treated his Jewish faith when he ran for vice president in 2000. Both broke barriers as representatives of minority religions. But Kennedy made the case for his own election on the grounds that his religion was not at all important to his role as a politician. His central assertion, politically necessary at the time, was that if ever his faith came into conflict with the Constitution or the public interest, he would resign. Joe Lieberman’s approach could not have been more different. He spoke at length about the importance of his faith and about the legitimacy of a politician bringing his or her faith to the public arena. Notice: To win acceptance from Protestants, especially Evangelical Protestants, it was absolutely essential for Kennedy to play down his faith. But when Lieberman did the exact opposite, by playing up his faith and speaking of God, this was seen as an effort to reassure and win over the very same groups of Evangelical Protestants (or perhaps their children and grandchildren).

In truth, Lieberman was simply more religious than Kennedy was. But their different approaches also reflected different historical moments. In Kennedy’s time, the fear to be addressed among conservative Protestants was that a politician was not a Protestant. In Lieberman’s time, the fear to be addressed among conservative Protestants was that a politician was not religious enough. This is a huge historical shift.

Dionne says that

the new politics of religion is not about driving religion out of the public square. It is about rethinking, again, religion’s public role. It is the latest corrective in our ongoing national debate over religious liberty, not a repudiation of religion’s social and political role.

But I'm not so sure. I think that the current politics of religion is very much a debate about whether religion should be in the public square or not. I do think that, for electability's sake, any candidate for President will have to show the right amount of religiosity. And I think that we are very very far from a place where an openly declared atheist could get elected. But could a Christian pastor (like Mike Huckabee, or if you can imagine it, a figure like Martin Luther King or Dorothy Day) get elected? I don't think so. I think these people take God as revealed in Christ too seriously. I think that the American people will demand someone who believes in a God who always puts American interests first.