Religion also reinforces the parties’ contrasting Americas.

White Christians account for 69 percent of all adults who identify as Republicans, according to the Pew Research Center’s massive religious-landscape survey. The last time white Christians equaled that much of America’s total population was 1984—the year of Ronald Reagan’s landslide reelection. Today, white Christians have fallen below majority status, to just 46 percent of the adult population. The change is even more pronounced among Democrats, less than one-third of whom are white Christians. Another third of Democrats are nonwhite Christians.

But the party’s largest group (around 35 percent) is comprised of people from all races who identify with non-Christian faiths, or increasingly, with no religious tradition. Those non-Christians are growing rapidly across American society—but in the entire population they likely won’t match their current level among Democrats until after 2020.

Similarly, data from Pew’s religious-landscape study shows that nearly three-fifths of Republicans are married—a level last reached in the overall adult population in 1994. Today just under half of American adults are married. Among Democrats, the number is lower still: barely over two-in-five. Likewise, the share of Republicans who live in a household with a gun (54 percent) equals the share in society overall in 1993. Since then, gun ownership among the general population has dropped to about 40 percent, while falling even lower (around one-fourth) among Democrats.

From these contrasting experiences, the parties now separate, above all, by their attitude toward the growing diversity and cultural changes remaking America.

As I’ve written, Republicans represent a coalition of restoration centered on the groups most unsettled by the changes (primarily older, noncollege, rural, and religiously devout whites). Democrats mobilize a coalition of transformation that revolves around the heavily urbanized groups (millennials, people of color, and college-educated, single, and secular whites, especially women) most comfortable with these trends.

A December national poll by the nonpartisan Public Religion Research Institute mapped the chasm between those perspectives. The survey found that almost three times as many Republicans (53 percent) as Democrats (19 percent) agreed both that “immigrants are a burden” on American society and that “the values of Islam are at odds with American values and way of life.” Nearly four times as many Democrats (43 percent) as Republicans (12 percent) rejected both ideas.

“The issue of immigration, Syrian refugees, and the issue of Muslims are all in the same basket,” says Daniel Cox, the PRRI’s research director. “They raise fears about security—whether that’s national security or economic security—and fear of cultural change. These are all things that the white working class is really struggling with.”