In 2010, the bestselling atheist Richard Dawkins, in the “On Faith” section of the Washington Post, called the pope “a leering old villain in a frock” perfectly suited to “the evil corrupt organization” and “child-raping institution” that is the Catholic Church. Nobody seemed to mind very much. Three years later, in a throwaway Tweet, Professor Dawkins observed that “all the world’s Muslims have fewer Nobel Prizes than Trinity College, Cambridge. They did great things in the Middle Ages, though.” This time round, the old provocateur managed to get a rise out of folks. Almost every London paper ran at least...