"You shall wipe out the memory of Amalek from under the heaven—you shall not forget."  Thus the Torah (Deut. 25:19) enjoins the Jews. Amalek is the name of a nation which, during the exodus from Egypt, had attacked Israel from behind, murdering the stragglers and the weak, at a place called Rephidim (Deut. 25:17-19; Exod. 17:8-16). What concerns us here is the contradictory nature of that commandment: it is not possible to "wipe out the memory" of an event, and simultaneously "not forget." Traditionally, Jewish commentators (for example, Maimonides) have resolved this issue by pointing to different modes of memory: Amalek's memory is to be wiped out from the written record, while his treachery should be orally remembered. This, however, begs the issue, for even if this kind of split memory was possible, the enemy's name would still remain—in several separate passages—in the Torah. The Torah commands us to do that which it itself refuses to.
The case of Amalek is significant in that it is a relevant example of a community trying to deal with a traumatic experience. Remembering seems to grant immortality to the perpetrators, forgetting would be disloyal to victims and cruel to survivors, depriving them also of experience and knowledge, and thus making them vulnerable again. Beyond that, the story of Amalek addressesPage 184 the crucial question of radical evil in history, its specificity and the reactions it elicits. Both issues surface each time a community is confronted with a particularly violent and treacherous attack. How to remember the victims without immortalizing the perpetrators? How to have the understanding of their motives, which is necessary if they are to be resisted, without creating a semblance of an understanding for such, which would betray the memory of the victims?
The dilemma of memory/oblivion is not the Torah's alone. We all remember the perpetrators of evil, thus granting them a functional immortality, much better than we remember the providers of good. Our memory is populated by Amaleks; indeed, they may at times become the founding-stones of our identity. Emil Fackenheim's "614th Commandment" (to supplement the 613 contained in the Torah) states this with terrible clarity:
Jews are forbidden to grant Hitler posthumous victories. They are commanded to survive as Jews lest the Jewish people perish. They are commanded to remember the victims of Auschwitz lest their memory perish. They are forbidden to despair of man and his world, and to escape either into either cynicism or otherworldliness, lest they cooperate in delivering the world over to the forces of Auschwitz. Finally, they are forbidden to despair of the God of Israel, lest Judaism perish. 
Apart from the first sentence of the quote, there is nothing in it—if one substitutes "evil" for "Auschwitz"—which could not have been said by any earlier Jewish teacher, including Moses himself. What Fackenheim does is to introduce Hitler, and not God, as the prime reason for obeying God's commandments.
It is not difficult to understand why the Canadian theologian resorted to this extreme measure. The experience of the Shoah  had made many Jews turn away from their religion, any religion, or even any Jewish identity—in protest against the seeming indifference of the God of Israel to the murder of His people. By formulating his 614th Commandment, Fackenheim puts them in what anthropologist and psychiatrist Gregory Bateson tagged a "double bind" and Joseph Roth's Yossarian would call "catch-22." In brief, Fackenheim tellsPage 185 the Jews that if they reject their identity, they will not be punishing God, but rewarding Hitler.  Even if you no longer can believe in God, Fackenheim seems to be saying, you still have to keep believing in Him; even if you no longer want to be Jewish, you still have to retain your identity. Otherwise you will place yourselves on the side of those who were responsible for your suffering in the first place. For Fackenheim, then, "remembering Amalek" becomes the central commandment—and thus, of course, is Amalek immortalized.