Pope Francis has fascinated the world with his humility, his compassion, and his radical vision for the Church. He has welcomed the homeless into the Vatican, embraced people with diseases, and shaken a complacent hierarchy. Shepherds, he said, should acquire the smell of the sheep. In short, as he has urged young people to do, he swims against the tide. John L. Allen, Jr., who has covered the Vatican for CNN, the National Catholic...