There is an Afghan grocery store on the blocks outside the main train station in Munich. Halal food counters are sprinkled amid the cathedral spires and beer halls. Nearly one of every three residents you meet in town is not German.

It’s a decent approximation of what many European cities, and European people, look like today. And a different Europe from the one the Trump administration says it wants to be friends with.

Marco Rubio, the U.S. secretary of state, tried to soothe a year of friction between the United States and its trans-Atlantic allies on Saturday at the Munich Security Conference. His speech there reiterated America’s commitment to Europe but wrapped it in historical and cultural ties that seemingly exclude large sections of the current European population.

“We are part of one civilization: Western civilization,” Mr. Rubio told a crowd of anxious diplomats in Munich. “We are bound to one another by the deepest bonds that nations could share, forged by centuries of shared history, Christian faith, culture, heritage, language, ancestry.”

The United States and Europe are indeed pillars of what historians refer to as Western Civilization, which has roots typically traced to ancient Greece.

Their modern relationship — and the bonds Mr. Rubio said held it together — has been changed by demographic trends, including new arrivals and rising secularization.

Christianity is declining across much of the continent. In Europe’s three largest economies — Britain, France and Germany — less than half of residents now identify as Christian, according to survey data by Bertelsmann Stiftung, a nonpartisan foundation. The ranks of the religiously unaffiliated are growing, according to data by the Pew Research Center and others.

After a decade-long influx of migrants from the Middle East and elsewhere, the share of Muslims across Europe has ticked up, to about 6 percent in 2020, according to Pew. The Jewish population has declined slightly and remains below 1 percent.