If Clinton had matched this cultural conservatism with decency in his private life, Al Gore would have won re-election as his heir and the larger story of the center-left might have been entirely different. But instead, from the mid-2000s onward, the leftward flank of the Democratic Party looked at the country’s changing demographics and growing social liberalism and decided that Clinton’s compromises with cultural conservatism weren’t as politically necessary as they had been (which was true), and that therefore they were free to become increasingly ideologically maximalist on everything touching gender or race or sexuality or immigration (which was … not true).

In this sense the story of the Democrats’ struggles over the last 15 years is a story of a party that has consistently moved leftward faster than the also-changing country, and consistently overread victories — on same-sex marriage above all — as a template for how every cultural battle should play out. It’s a story of a new feminism that’s pushing the party ever-further from the center on abortion, of a new cohort of white liberals who are actually to the left of many African-Americans on racial issues, of an activist base that brands positions that many liberals held only yesterday as not only mistaken but bigoted or racist or beyond-the-pale.

And in this part of the Democratic coalition’s story, the center-left’s role has been extraordinarily passive, essentially following the cultural left a tiny bit more slowly rather than trying to devise a more moderate approach. You can find hints of what such a moderate approach might look like in intellectual projects like Jonathan Haidt’s Heterodox Academy, or in the probing, evenhanded culture-war reportage of the magazine writer Jesse Singal (whom I hesitate to even praise because it will do him no favors on the internet). But that cultural moderation has no substantial political form, no important champions within the Democratic Party. It has Joe Manchin and Tulsi Gabbard, maybe, but they are eccentric figures; elsewhere among the Democrats there is little interest in considering all the different ways that cultural extremism costs them votes.

Which means that if the center-left abdicates, DeLong-style, on economic policy, the Democratic Party as a whole will have moved to the left on every front, writing off not only the possibility of compromising with Republican politicians (which, for now, might be understandable) but also the possibility of winning over voters who would almost certainly be Democrats if the party still occupied the cultural terrain that it held in 2000 or even as late as 2008.

Because the country as a whole has also shifted left since 2000, that kind of writing-off will not prevent the Democrats from winning elections; it probably won’t prevent them from beating Donald Trump. But it will stand in the way of any dramatic left-of-center consolidation, any kind of more-than-temporary Democratic governance. And if the center-left feels itself irrelevant in an age of socialist ambition, then taking up the task of rebuilding a cultural center, and a Democratic Party capable of claiming it, seems like the task that might actually be suited to the times.

Sadly the rest of the DeLong thread didn’t take up that possibility. It degenerated, instead, into a howl against Republican fascism and a post-Protestant sermon about how liberal America can build the true and only heaven, the real shining city on the hill.

Which suggests that to reckon with the possibility that making liberalism a pseudo-church might be a problem, not an aspiration, we need a very different center-left from the one surrendering today.