When Iranian President Mahmoud Ahmadinejad invited Holocaust deniers from around the world to “re-envision history” by shedding darkness on our people’s darkest hours, white supremacist and former Ku Klux Klan and American Nazi leader David Duke spoke on behalf of “the oppressed people of the world” and was given an opportunity on CNN to call Wolf Blitzer a tool of the Zionist conspiracy.

A fervently Orthodox rabbi who attended last month’s conference hugged his Iranian host and decried the “Zionists’ manipulation of Jewish suffering.”

These images seem absurd. But Ahmadinejad was only making real an incredible midrash, a rabbinic tradition envisioning wicked Haman convincing ancient Persian King Achashverosh to endorse his plot against the Jews by retelling the Exodus as a story of Israelite terrorists who mercilessly slew their Egyptian hosts and ran roughshod through the desert behind their bloodthirsty chieftain, Moses.

In this midrash, Haman’s ancestors the Amalekites are not the cruel murderers who fall upon the Israelites when they are weak from their travel, but a peaceful people forced to take pre-emptive action against the dreaded followers of Moses. But what can we expect from the villain of the Purim story?

Purim is known universally as a time for absurdity. Masks cover the faces around us, groggers drown out the names of the wicked and tradition enjoins us to take temporary leave of our sobriety to the extent that we will even confuse the blessedness of the hero Mordechai with the cursedness of the evil Haman. On Purim we revel our way through both a looming genocide and the bloodshed that results from thwarting the designs of the wicked.

How can we be so unserious about these matters, knowing the truth about the history we have lived and the very real dangers that still lurk? When the leader of modern Persia (Iran) convenes a conference of Holocaust deniers, publicly contemplates a world without Israel and openly seeks nuclear weapons, should we be putting on Purim shpiels?

The Megillah leaves no ambiguity about the massacre that would have been perpetrated by Haman and his followers. Only the vigilance of Mordechai and the courage of Esther stood in the way of his plan.

Yet the Purim holiday also highlights the absurdity of this salvation. The name Purim denotes the lottery of chance that not only was used to choose the day on which Haman’s pogrom would take place, but also stands for the stroke of luck by which the Jews happened to be in the right place at the right time to stop him.

The Book of Esther, whose name means “hidden one,” does not contain a single overt reference to the Divine or mention any supernatural events. What turned out to be a miracle was just as close to being a devastating massacre.

Against this backdrop emerged the traditional observance of Purim with its escapist masks, shpiels and abundant l’chaims.

Our topsy-turvy retelling of the Purim story points the way out of the trap between moral relativism and uncritical absolutism. Here is the difference between “cursed is Haman” and “blessed is Mordechai”: The identification of a great evil does not mean that every action we take to oppose it is good.

It does not take a lot of drinking to lose sight of this fragile distinction. This insight became even harder to hold on to in the aftermath of the Sept. 11 attacks, when even al-Qaida has been upstaged by the fear unleashed by Ahmadinejad and his implacable antipathy toward Israel.

Purim’s message for us today runs deeper than either the straightforward malevolence exhibited in the Book of Esther or the wild free-for-all that marks the holiday’s observance.

At the heart of the Purim tradition lies a paradox: Evil is real and must be confronted, but we ourselves are capable of losing our own moral compass when faced with terror. Will we be able to stay alert to real danger and at the same time retain the clarity necessary to make just, informed choices?

What holds these aspects of Purim together is Haman’s relationship to Amalek. On the Shabbat before Purim, Shabbat Zachor, we read the Torah’s commandment to remember that the Amalekites attacked without mercy when they chanced upon the Israelites coming out of Egypt. Amalek “happened” upon us, just like we “happened” to be in the right place to stop Haman.

We must remember baseless hatred is both absurd and very real. At the same time, when we celebrate Purim, we embrace the topsy-turvy uncertainty that makes us human.

Rabbi Michael Bernstein is the spiritual leader of Congregation Beth Am Israel in Penn Valley, Pa.