... both Waldman and Ross seem to be ignoring a fairly large elephant in the corner: Communists — or Marxists, doctrinaire socialists, dialectical materialists, whatever you want to call them. Here was a very tribal bunch. They were dedicated to the overthrow of religion and religious opiates. They protected themselves in tribal fashion in academia, government and politics. They defined themselves largely by what they hated. Etc, etc. Indeed, it's worth remembering that both Marx and Engels came to their Communism via their atheism rather than the other way around (Josh Muravchik's book Heaven on Earth makes this point vividly).
Oh, definitely - but it's important to distinguish the American experience from the European here. While Communism was certainly a tribal phenomenon in the American context, it was never a mass phenomenon in the way that the new secularism seems to be, or seems capable of becoming. It was an intellectual tribe, but not a political demographic. In Europe, by contrast, Marxism was a mass movement, as were various other anti-clericalist ideologies. That's why my Atlantic piece argues that the rise of a politically-assertive secular demographic in American life, however narrow its appeal, represents an unexpected case of continental convergence, in which America's religious politics are likely to look at least somewhat more like Europe's going forward. (And vice versa, I suggest, given the culture-war battles provoked by the rise of Islam across the Atlantic.)
Though it's certainly possible, as a commenter points out, that if the religious right fragments (and the Republican Party goes into the political wilderness), the nascent mass secularism will fragment as well, and what seems to be an anti-clerical dawn in American life will prove to be a false one. At the very least, there's going to be ebb and flow in the culture wars, and since we've just experienced a high tide in the Bush years it's likely that passions will cool off somewhat in the short run. Still, my sense - based both on the data and on my own personal experience - is that mass secularism has put down sturdier roots in American soil of late than anyone would have expected, say, thirty years ago, and that it's both something new and something that's here to stay.