Once upon a time, Americans settled around the television to enjoy a white Christmas together. Nowadays, it seems, they are too entrenched on opposite sides of the “war on Christmas”, or commoditising it to oblivion, to remember Bing Crosby’s crooning. To say the US is a civilisation divided may strike some as an overstatement.

For the most part, the country still speaks one language. Black and white, straight and gay, Jewish and Muslim all flock to the latest Star Wars movie. Interest in the Oscars and the Super Bowl obliterates sociological distinction. So too does fear of economic insecurity. These things unite most Americans.

Yet the things that divide the country are growing. If you listen to the Republican presidential debate, one message overrides all. Conservatives do not just disagree with President Barack Obama — they hate him profoundly. When asked if they would back a Donald Trump nomination, even the most moderate Republican says anyone would be better than this “feckless, weakling” president, to quote Chris Christie, the New Jersey governor.