A few days before the sixth anniversary of 9/11, a young man ranting in Arabic accosted a rabbi walking home from his synagogue in an upscale neighborhood of Frankfurt, and stabbed him. As he shoved the blade of his pocketknife into the rabbi's stomach, he switched from Arabic to German and told the man: "You sh---- Jew, I'm going to kill you." The rabbi survived, and Jewish leaders in Germany were outraged and condemned the barbarism, but moderated their criticism.

"We oppose leveling blanket accusations at the Muslim community because the majority of Muslims in Germany condemn acts of violence in the name of Islam," Dieter Graumann, the vice president of the German Jewish Council, said. But he observed that Islamist hate preachers regularly exhort young Muslims to carry out jihad against Jews, and asked why so few leaders of the Islamic community in Germany speak out against violence in the name of Mohammed.

This attack on the rabbi coincided with a visit to Washington by my daughter's family from Berlin. They brought rave reviews of Germany's largest synagogue, just now reopened in their neighborhood of Prenzlauer Berg in East Berlin. The Nazis set the synagogue afire on Kristallnacht and, adding insult to injury, used the ruined synagogue as a stable for horses. The renovation is hailed as a symbol of regeneration and revival of German Jewish life annihilated by the Holocaust. Like all synagogues in Germany, 24-hour police protection is required to prevent violence from Neo-Nazis and Islamist terrorists.

While the Germans have made enormous efforts to atone for the Holocaust, the attempted murder of the rabbi invites attention to a contemporary problem. Radical Islamists who go undercover in Germany fuse anti-Semitism with hatred for America, and the antecedents of this hatred are rooted in the Germany of Adolf Hitler.

Matthias Kuntzel, a Hamburg-based political scientist, writes of this in the current Weekly Standard. In "Jew-Hatred and Jihad: The Nazi Roots of the 9/11 Attack," he traces the connection to Arab and Muslim hatred of the Jews that fed the fantasies of der Fuehrer. He suggests it's no coincidence that assaults on the World Trade Center were orchestrated by an al Qaeda cell in Hamburg, where five of the conspirators -- from Egypt, the United Arab Emirates, Lebanon, Yemen and Morocco -- met with sympathizers for regular meetings of a "Koran circle."

He, like a growing numbers of Germans, is astonished that reporters and commentators along with policy-makers have made so little of the Islamist rhetoric that links Islamism with Nazism in both ideology and strategy. "After World War II, it became apparent that the center of global Jew-hatred was shifting from Nazi Germany to the Arab World," he writes.

The Muslim Brotherhood, which may have begun as a rebellious group against British colonialism before the war, aimed violence directly against Jews and Zionism when the war was over. They took the anti-Semitic conspiracy theories as their own, drawing on "Mein Kampf" and the infamous czarist fiction, "The Protocols of the Elders of Zion." They borrowed rhetoric from the German and Italian radio broadcasts that inflamed Arab anti-Semitism during the war.

A major figure connecting Nazi and Islamist ideologies was Amin al-Husseini, a self-styled "grand mufti" of Jerusalem who fomented riots against the Jews in the 1920s and ordered the murder of any Muslim who traded with Jewish settlers. Adolf Eichmann visited him in Palestine in the 1930s; he was a friend of Heinrich Himmler. He was a guest of Hitler in Berlin from 1941 until the end of the war in 1945 and directed the Muslim SS in the Balkans. He was responsible for stopping the Bulgarian government from releasing thousands of Bulgarian Jewish children to travel to Palestine. "It was he," says historian Paul Johnson, "who first recruited Wahabi fanatics from Saudi Arabia, transforming them into killers of Jews -- another tradition that continues to this day."

What's important about the Nazi-Islamist connection is the way it inspires terrorists today. It's fashionable to say that anti-Zionism is not anti-Semitism, but that's misleading. In its charter, the Muslim Brotherhood in Palestine, which has morphed into the terrorist organization Hamas, lists conspiracy theories blaming the Jews for everything from the French Revolution to the communist revolution.

Hitler dreamed of building a huge warplane able to fly from Berlin to Manhattan and back to launch a small, light suicide-like bomber into the skyscrapers of Wall Street, which he believed was the "center of Jewry." Mohammed Atta, the 20th conspirator of 9/11, regarded Wall Street as a nest of Jews as well. Matthias Kuntzel describes Hitler's obsession as the fantasy foreshadowing 9/11. Hitler's fantasy bomber, meant to be shoved into the belly of Wall Street, foreshadowed the knife shoved into the belly of a rabbi in Frankfurt.