David Kertzer put down his cappuccino, put on his backpack and went digging for more Vatican secrets.
“There’s an aspect of treasure hunting,” said Mr. Kertzer, a 74-year-old historian.
Moments later he cut through a crowd lined up to see Pope Francis, showed his credentials to the Swiss Guards and entered the archives of the former headquarters for the Holy Roman Inquisition.
Over the last few decades, Mr. Kertzer has turned the inquisitive tables on the church. Using the Vatican’s own archives, the soft-spoken Brown University professor and trustee at the American Academy in Rome has become arguably the most effective excavator of the Vatican’s hidden sins, especially those leading up to and during World War II.
The son of a rabbi who participated in the liberation of Rome as an Army chaplain, Mr. Kertzer grew up in a home that had taken in a foster child whose family was murdered in Auschwitz. That family background, and his activism in college against the Vietnam War, imbued him with a sense of moral outrage — tempered by a scholar’s caution.
The result are works that have won the Pulitzer Prize, captured the imagination of Steven Spielberg and shined a sometimes harsh light on one of earth’s most shadowy institutions.
Mr. Kertzer’s latest book, “The Pope at War,” looks at the church’s role in World War II and the Holocaust — what he considers the formative event of his own life. It documents the private decision-making that led Pope Pius XII to stay essentially silent about Hitler’s genocide and argues that the pontiff’s impact on the war is underestimated. And not in a good way.
“Part of what I hope to accomplish,” Mr. Kertzer said, “is to show how important a role Pius XII played.”
The current pope, Francis, said “the church is not afraid of history,” when in 2019 he ordered the archives of Pius XII opened. But as Francis wrestles with how forcefully to condemn a dictator, this time Vladimir V. Putin of Russia, Mr. Kertzer has unearthed some frightening evidence about the cost of keeping quiet about mass killings.
Mr. Kertzer makes the case that Pius XII’s overriding dread of Communism, his belief that the Axis powers would win the war, and his desire to protect the church’s interests all motivated him to avoid offending Hitler and Mussolini, whose ambassadors had worked to put him on the throne. The pope was also worried, the book shows, that opposing the Führer would alienate millions of German Catholics.
The book further reveals that a German prince and fervent Nazi acted as a secret back channel between Pius XII and Hitler, and that the pope’s top Vatican adviser on Jewish issues urged him in a letter not to protest a Fascist order to arrest and send to concentration camps most of Italy’s Jews.