Many readers of the New York Times no doubt believe that Pope Pius XII was "Hitler's Pope." John Cornwell's bestselling book told them that, and it's been reaffirmed by Garry Wills, Daniel Goldhagen and other writers since. It's been said so often in fact that most well-read liberals know it for a certainty. The only trouble is: it isn't true. Not only does it contradict the words of Holocaust survivors, the founders of Israel, and the contemporary record of the New York Times, but even John Cornwell, the originator of the phrase "Hitler's pope," has recanted it saying that he...