It’s difficult to mediate a grudge match between Donald Trump and the Pope. (Yes, it has come to this. But the less lament about the state of crazy in American politics, the better.) While visiting Mexico and encouraging the U.S. to address the growing humanitarian crisis afflicting migrants, Pope Francis responded to a question about Trump’s immigration policies. “A person who thinks only about building walls, wherever they may be, and not building bridges, is not Christian. This is not the gospel,†he told journalists. Trump responded with his predictable humility. “For a religious leader to question a person’s faith...