I t’s no accident that the figure emerging as the global challenger to the might of Donald Trump is a priest in white, known as Pope Leo XIV. In recent weeks, the pope has issued a string of barely coded denunciations of the US president, unfazed by the insults that have come his way in return. It’s no longer fanciful to imagine that what an eastern European pontiff, John Paul II, did by confronting the Soviet empire in the 1980s, an American-born pope may do in the 2020s by daring to speak truth to the would-be emperor in the White House. Of course, several heads of government have stood up to Trump too. Canada’s Mark Carney has done it most explicitly, while his European counterparts have taken a stand by refusing to join the president’s reckless, wrong-headed war on Iran. But none has the global reach of the leader of the world’s 1.4 billion Catholics. There’s more to it than numbers, though.…