(UNDATED) As a child growing up in post-World War II America, the Jewish holiday of Purim was always filled with costume parties, satirical skits, carnivals, tasty sweets, and gaiety.

The highlight of the holiday, to be celebrated March 10 this year, is the public reading of the Megillah (the scroll containing the biblical book of Esther) in synagogues. The Megillah’s 10 chapters, the basis of the holiday, comprise a wonderfully compact short story.

Purim tells how Haman, the wicked prime minister of ancient Persia (today’s Iran) was consumed with hatred and cast lots, or dice — purim in Hebrew — to determine the date for the mass murder of the Jewish community, perhaps the first recorded attempt at genocide.

The deadly plan was thwarted at the last moment by Persian court intrigue involving the personal intervention of Esther, the Jewish queen, and Mordecai, her politically adept uncle. As a remembrance of their deliverance from death, Jews are commanded to celebrate every year.

But Purim’s depressing story line seemed far removed from my own life, especially following the destruction of Nazi Germany and the end of the Holocaust in 1945. I now realize the holiday’s ominous theme was consistently played down.

It was widely believed that anti-Semitism had at last been eradicated. After the mass murder of 6 million Jews in Europe, after so much blood, suffering, and pain, we assumed the world had permanently learned the ghastly lesson of anti-Semitism, whether in long ago Persia or 20th century Germany: hatred of Jews and Judaism is a social pathology, a cancer that always begins with ugly rhetoric and invariably ends in physical violence — including murder.

However, in those halcyon days of my youth, whenever there were dire warnings about a resurgence of anti-Semitism somewhere on the globe, many of us responded to such pessimistic talk with the protective device of psychological denial. Verbal and physical attacks on Jews led by neo-Nazis, skinheads and their ilk were quickly minimized, easily explained away, or simply ignored. It was a clear case of believing French philosopher Emil Coue’s famous teaching that “in every day and in every way, we are getting better and better.”

But, of course, both we and Coue were wrong.

This year’s Purim celebrations will still be filled with the usual merrymaking, but the recent surge of anti-Semitism, especially in supposedly progressive democratic Europe, provides a grim backdrop to the usual holiday festivities. Nearly 65 years after the collapse of Nazi Germany, there are today numerous violent attacks against Jewish institutions, including synagogues, as well as physical assaults on individual Jews on the very continent of the Holocaust. Hitler and his followers must be smiling from their well-deserved places in hell.

While some anti-Semites employ the crude anti-Jewish caricatures of the Nazi era, the “new” anti-Semitism is frequently an attack on Israel’s right to exist, linked with the false assertion that Israel’s relations with the Palestinians are comparable to the anti-Jewish policies of Nazi Germany. It is an obscene equation.

Another anti-Semitic lie is to deny the historic reality of the Holocaust itself. In recent days, former German chancellor Gerhard Schroder found it necessary to tell Holocaust denier Mahmoud Ahmadinejad, the Iranian president, that the mass murders really took place.

Alarmed by the sharp rise of anti-Semitism, more than 100 legislators from 42 nations recently convened in London to chart an aggressive and hopefully effective response to this serious problem. The lawmakers called upon their governments to “never again allow the institutions of the international community to be abused for the purposes of trying to establish any legitimacy for anti-Semitism.”

British Prime Minister Gordon Brown became the first national leader to sign the London Declaration this week (Feb. 22-28).

British Parliament member John Mann, the conference chair, issued a bleak warning: “The Internet, the globalization of the media, a resurgence of the extreme right and an anti-Zionist hard left have combined to create a febrile environment in which the spread of old and new anti-Semitic theories and attitudes have been able to gain traction with alarming ease. Anti-Semitism is a touchstone for other ills within wider society and unless we move to address its spread now, and as a matter of the utmost urgency, we will all pay a heavy price.”

Tragically, Purim tells a thoroughly modern story.

(Rabbi Rudin, the American Jewish Committee’s senior interreligious adviser, is the author of “The Baptizing of America: The Religious Right’s Plans for the Rest of Us.”)