On the evening of May 24 last year, 2,000 left-leaning Christians gathered for a candlelit vigil outside the White House. The group’s leaders, including the Episcopal Bishop Michael Curry – fresh from his starring role at Britain’s Royal Wedding – read out a statement against Donald Trump’s presidency. “We reject ‘America first’,” they announced, “as a theological heresy.”

The word might sound outdated. But Trump has helped to make heresy accusations fashionable again. When he invited the pastor Paula White to pray at his inauguration, conservative Protestants such as Russell Moore and Erick Erickson denounced White as a “heretic” for her views on the Trinity. (She rejects the charge.) Heresy accusations transcend the left-right divide.