"White Christian America is dying," proclaims the headline on a Monkey Cage blogpost by the perceptive political scientist John Sides. Like many headlines, it's an exaggeration of the thrust of the article that follows, which is an interview with Robert Jones, head of the Public Religion Research Institute, on his new book The End of White Christian America, based on PRRI and other research on religious beliefs and practices of Americans.

Sides's questions and Jones's answers are pretty much neutral in tone, but many readers will detect a tone of triumphalism in the book's title and in the thrust of its argument. You white Christians have been the majority for a long time, but it's not going to be your country any more — or so they seem to be saying. That's a variation on the message that demographic analysts like National Journal's Ron Brownstein have been delivering for some time. The percentage of voters classified as "white" has been declining and will continue to do so, to the extent that the Democratic party might emerge with a permanent electoral majority.

Some observations:

1. Predictions of inexorable political doom for one of our major political parties are likely to be wrong — as they have been since the demise of the Whigs in the middle 1850s. Politicians adapt to demographic change, new issues arise that divide voters in different ways, events change the political landscape. My observation is that voters who are self-consciously part of a demographic minority tend to vote more cohesively. Black Americans are the prime example, of course, and have been for the last 150 years, and for reasons every reader should find easy to understand. There are others: Catholics, according to Gallup, voted 78 percent for John Kennedy in 1960.

If you keep telling "whites" (a category not considered useful when I started analyzing election data, since almost all voters were "white" then) or white Christians that they are headed to minority status, they are going to start voting like members of a self-conscious minority group. Arguably they already have. The exit poll recorded that 59 percent of whites voted for Mitt Romney in 2012, the highest white percentage for any Republican candidate in history except for landslide winners Richard Nixon in 1972 and Ronald Reagan in 1984. (Warren Harding got 60 percent of total votes in 1920, but since just about all of blacks then allowed to vote surely voted for him his percentage among whites must have been 59 percent or lower.)

Some analysts have argued that no Republican could run significantly better among whites, because almost none had done so before. Why not? May and early July polling suggested Donald Trump, with his higher-than-Romney support from non-college-graduate whites, had the potential to do so — a potential he seems to have effectively squandered. Certainly higher proportions of whites have voted Republican in other races, and not only in the Deep South: look at Larry Hogan's win for governor of Maryland in 2014, in which he got the votes of about 70 percent of whites.

2. Robert Jones's criterion of whether someone is a Christian is whether they have joined a church. This would have made white Christians a minority during much of the nineteenth century, since church membership was far from universal then.

3. Jones notes that the decline of the white Christian percentage is primarily the result of Millennials not joining a church. One reason he cites is churches' opposition to same-sex marriage. That's plausible. But he omits another plausible reason, that Millennials are less likely to have children than previous generations, and the most recent statistics show a record low number of births in the United States.

People tend to join churches when they have young children. That's one reason many churches run nursery school programs: they hope that young parents will join their congregations. That may also be one reason secular liberals want to establish government-run (and union-member-staffed) universal preschool: To reduce what they regard as the malign influence of churches.

4. Robert Jones apparently thinks that in order to increase membership churches need to abandon opposition to same-sex marriage and build "diverse" multiracial congregations. My own sense is that with the legalization of same-sex marriage throughout the country by the Supreme Court, the issue is going to become less salient for many people.

On a broader point, the experience of the American religious marketplace, as scholar Rodney Starke has shown, is that the churches which attract members are those who make significant demands in terms of both behavior and belief. Agnostics and atheists are free to sleep in on Sunday. Unitarianism is not thriving. On the diversity point, people join voluntary associations like churches because they think they have much in common with other members, that they trust they will be similar in belief and behavior.

Sectarianism is as American as apple pie. We have not only had black churches, we have had separate Northern and Southern churches. The American Catholic Church, run by Irish-Americans for most of its history, has had identifiable Italian and Polish parishes. It's nice if people of different ethnic or racial heritage decide to participate in a congregation together. But it doesn't seem likely to be a major driver of increased church membership.

5. Jones and Sides don't focus much, if at all, on the positive effects of church membership. Churches are sources of what Robert Putnam and Charles Murray call social connectedness or social capital; they knit people together, they provide help and guidance through difficult times and on difficult issues, they inspire as Arthur Brooks has documented an immense percentage of American charitable giving and volunteering.

Churches were critical in mobilizing support for abolition of slavery and (with black churches playing the major role) equal civil rights. As a non-Christian and, if this matters, a supporter of same-sex marriage before Barack Obama or Hillary Clinton, I'm far from sure that America is better off with fewer white Christian church members.