Throughout the Diaspora there are alienated Jews on the fringe whose primary involvement in Jewish life is centered on undermining the Jewish state. Now they are seeking to establish themselves as a respectable alternative Jewish voice. This is the price we are paying for having long buried our heads in the sand, failing to isolate from the mainstream Jews who dedicate themselves to delegitimizing and demonizing Israel. The potential damage they are capable of inflicting upon us cannot be underestimated. Jews defaming their own people is hardly a new phenomenon. Their presence is evident throughout history from the age of antiquity on. In the Middle Ages, the most virulent promoters of anti-Semitism were Jewish converts. During the Emancipation period, Jews committed to universalism, socialism and other "isms" were inciting hatred against their kinsmen, as exemplified in the anti-Semitic outbursts of Karl Marx and the late 19th-century Russian Jewish social revolutionaries, who justified pogroms as a necessary lubricant to create a revolutionary climate. Jewish self-haters were silent during the Holocaust era because the Nazis targeted all Jews. After the war, Jewish communists and their "progressive" fellow travelers reemerged as the most fervent apologists of Stalinist crimes. During the campaign to liberate Soviet Jewry, they denied Soviet anti-Semitism and defended - even applauded - state-sponsored anti-Semitic show-trials and executions of their kinsmen. Like their contemporary successors, their effectiveness as spokesmen for our enemies was linked to the fact that they paraded their Jewish origins. However in contrast to today's Jews who demonize Zion, they were considered pariahs by mainstream Jews and clearly perceived by non-Jews as outcasts from their own people. TODAY THOSE delegitimizing the Jewish state are frequently indulged in respectable Jewish circles. Some Jewish leaders have even suggested that a "pluralistic" community should not discriminate against anti-Israel "dissidents." Much of the responsibility for misplaced tolerance of those promoting our destruction originates inside Israel. The vilest anti-Israeli propaganda has for years been emanating from tenured academics at Israeli universities. Now the problem has begun mushrooming out of control. In view of the fact that demonstrating hatred of Israel has become a key prerequisite for eligibility to membership of the "progressive" camp, one finds Jews at the forefront of the vicious campaigns demonizing Israel in virtually every country. Yet to accuse these renegades of indulging in self-hatred is considered as a cardinal sin in many circles. It is thus legitimate for Jews to defame Israel as an "apartheid state," accuse their kinsmen of behaving like Nazis, apply double-standards to Israeli behavior, accuse Israel of ethnic cleansing, war crimes, even genocide; it's even acceptable to call for dismantling Israel and replacing it with a binational state, or to support the "right of return" for Arab refugees - all in the name of communal tolerance. Yet to stand up and brand such views as extremist is deemed an expression of "Zionist McCarthyism." IT IS A pathetic reflection of our times that people such as Tony Judt, Marc Ellis, Norman Finkelstein, Jacqueline Rose and Tony Kushner are considered martyrs, and tolerance of their malicious efforts to delegitimize the Jewish state has become confused with freedom of expression. What a red herring. Insisting that Jewish demonizers of Israel comprise an extremist fringe and speak only for themselves does not represent suppression of free speech. Our enemies allege that condemnation of those delegitimizing Israel is designed to cover up and deflect legitimate criticism. Never mind that genuine friends of Israel - indeed, Israelis themselves - are often vociferous critics of this or that Israeli policy. But there's a difference between being critical of a policy and delegitimizing the Jewish state. Regrettably, efforts to obfuscate these polar opposites have increasingly been endorsed by much of the media. When American academic Alvin Rosenfeld wrote an essay for the American Jewish Committee exposing the double standards and deviousness of Jews challenging Israel's right of existence, he unleashed a storm and was accused of playing foul for supposedly branding all criticism of Israel as anti-Semitic. That he deliberately avoided using expressions like anti-Semitism and self-hatred was ignored. Yet once so-called liberals misrepresented his views, even mainstream New York Jewish trendies began to join the pack attacking Rosenfeld. At a time when Israel faces genuine existential threats, the audacity of the Jewish anti-Israeli camp has reached alarming levels. For example, a purportedly "Zionist" body demanded the right to introduce Israeli "refusenik" draftees to American campus students, describing their initiative as a "Zionist act of love," leaving mainstream Jewish campus groups divided whether to support such a bizarre proposal. Elsewhere a number of Jewish organizations which identify themselves as "pro-Israel" have been lobbying Congress to reject the community's mainstream positions, urging instead that Israel be pressured into pursuing policies contrary to its interests. MEANWHILE, in London the head of the only Anglo Jewish think tank cannot comprehend why his publicly stated belief that the Jewish state was a mistake and should be transformed into a binational state makes him ineligible to hold such a position. And the chair of this institute, who is also chair of Anglo Jewry's most important newspaper, has accused those calling for his director's resignation of behaving like McCarthyites. I recommend that our recently-appointed minister for Diaspora Affairs, Isaac Herzog, place the issue of legitimate versus illegitimate criticism of Israel high on his agenda, and convene a world conference of mainstream Jewish organizations who cherish the name of Israel and all it represents. They should adopt a united stand to expose as a sham the obscene pretensions of Jews who carry out diabolical campaigns to delegitimize Israel - and have the gall to claim that they do it out of a sense of Jewish values and justice! The writer chairs the Diaspora-Israel Relations Committee of the Jerusalem Center for Public Affairs and is a veteran international Jewish leader.