The recent Holocaust denial conference in Iran was beyond the pale, or so any thoughtful person might conclude. After all, the Holocaust is among the most documented events in human history. Yet, to conclude that this macabre event was an isolated event would be a mistake. For example, in an editorial (December 14), the respected Financial Times declared that the Iranian president, who sponsored what the paper aptly called this "grotesque carnival," is out of step with the larger Muslim world. His blatantly anti-Semitic remarks, the editorial stated, "give the impression that anti-Jewish bigotry is widespread across the Muslim world," when "in historical reality, anti-Semitism is a Christian disease." Not so fast. The truth is far more complicated. While anti-Semitism historically has been more virulent in European Christendom, leading up to the Holocaust, it has not been absent in the Muslim world. Some Muslim spokesmen would like the world to believe that any hostility is recent and linked to Israel, not Jews. But that is disingenuous in the extreme. As Hebrew University professor Robert Wistrich noted in a study entitled Muslim Anti-Semitism: A Clear and Present Danger, "The most basic anti-Jewish stereotype fostered by the Koran remains the charge that the Jews have stubbornly and willfully rejected Allah's truthâ€¦. There are some notably harsh passages in which Muhammad brands the Jews as enemies of Islam." These deeply entrenched images of the Jews have caused much grief over the centuries. Rather than debate the past, however, let's focus on the present. A 2003 American Jewish Committee study revealed widespread anti-Semitism in the Saudi educational system. As a ninth-grade language textbook typically asserted, "The Jews are wickedness in its very essence." Similarly, an eighth-grade grammar textbook, reflecting on the fate of the Jewish people, states, "Their end, by God's will, is perdition." An entire generation of Saudis - not to mention pupils in Saudi-funded schools elsewhere in the world, including, reportedly, some in the United States - is being taught this unvarnished hatred and contempt. In his widely-covered valedictory speech before the Tenth Islamic Summit Conference, outgoing Malaysian prime minister Mahathir Mohamad raged about the Jews who "rule this world by proxy." What was the reaction of the hundreds of leaders in attendance? Did any walk out? To the contrary, Mahathir received a standing ovation. TODAY, Hitler's Mein Kampf, the infamous Protocols of the Elders of Zion (the century-old tsarist forgery asserting a secret Jewish plot to control the world), and Der St rmer-like cartoons depicting Jews in the most grotesquely obscene manner enjoy widespread popularity and resonance in large swaths of the Arab and greater Muslim world. Fiery sermons in some major mosques rail against the Jews as the "sons of monkeys and pigs," and bizarre conspiratorial theories link Jews to every known calamity from 9/11 to the spread of communicable diseases. An important new documentary, "Anti-Semitism in the 21st Century: The Resurgence," was aired on PBS on January 8. It presented excerpts from Egyptian and Syrian television programs that propagate myths of Jews scheming to assert their rule and kidnapping non-Jewish children in a modern-day reenactment of the "blood libel." When the Egyptian producers were asked on camera if their work was anti-Semitic, with straight faces they claimed it was about history, not Jews, while a Syrian professor, with great solemnity, insisted that, yes, the portrayal of the Jews was accurate. To be sure, there are other Muslim voices urging mutual respect and interfaith harmony, reflecting an entirely different perspective. And while ancient Jewish communities that long predate the arrival of Islam have been driven out of most Arab countries, there remain small but significant Jewish populations in Morocco and Tunisia, and Jews in predominantly Muslim Turkey maintain an active communal life. The demonization and dehumanization of Jews has become a prominent feature of life in too many Arab and other majority-Muslim countries such as Iran. Yes, there is a long-standing conflict with Israel. But for the leaders of these tightly run governments to permit unvarnished anti-Semitism to become part of the daily fare of media broadcasts, school textbooks and Holocaust-denial conferences - whatever the denials or rationalizations - must be deemed unacceptable by the international community. Leaders and governments must be held accountable for their actions. And Western nations that have close contact with offending countries should raise concerns in bilateral and multilateral settings. Can it really be, for instance, that the US is prepared to turn a blind eye to what is being taught in Saudi textbooks about Jews (and Christians) because of our need for energy and export markets? Or that European nations will continue to deal with Iran in a business-as-usual fashion while its leaders deny the Holocaust and, for that matter, pursue nuclear weapons that they might one day use? Anti-Semitism, it should be recalled, is not only an assault on Jews, but on our common democratic values of mutual respect and pluralism. The writer is executive director of the American Jewish Committee.