It was supposed to be a purely patriotic occasion — President Trump banished the Philadelphia Eagles from their own Super Bowl victory celebration, replacing it with a “Celebration of America.” (Why? For much more on that, read my colleagues David Nakamura and Wesley Lowery’s report.)

Then the Marine Corps band struck up the familiar strains of “God Bless America.” When video of the ensuing moments went viral, many people speculated that perhaps the song is not actually so familiar to Trump. Champion of patriotism though he might be, his lips stopped moving during most of the lyrics.

Those lyrics have a storied history — one deeply entwined with America’s ever-uneasy relationship between religion and politics.

The song was written by an immigrant. Irving Berlin arrived in New York at age 5 as Israel Baline, the son of a cantor fleeing persecution of the Jews of Russia. During World War I, Berlin wrote “God Bless America.” The title was a phrase his immigrant mother fervently repeated during Berlin’s childhood, his daughter later said.