In 2016 I wrote an op-ed demanding that Black Lives Matter rescind the portion of its platform that describes Israel as an “apartheid state” involved in “genocide … against the Palestinian people.” I pointed out that the platform refers to no other country but Israel, despite the egregious records of many foreign countries with regard to police brutality. It is now four years later and these provisions of the platform remain intact. Defenders of Black Lives Matter argue that the inclusion of this critique against Israel in not antisemitic; it is merely anti-Zionist.

As a law professor for 50 years I frequently used “hypothetical cases” — the students called them “hypos” — to deepen the analysis of a problem. So please consider the following hypo: Imagine a world in which there was only one Black African nation — a nation built largely by previously enslaved Black men and women. Imagine further that this singular Black nation had a good record on the environment, on gay rights, on gender equality, on human rights, and on defending itself against attack from predominantly white nations. But as with all nations, the Black Nation was far from perfect. It had its flaws and imperfections.

Now imagine further that do-gooder organizations in America and around the world were to single out the Black nation for unique condemnation. For example, imagine that an environmental group or a gay rights group were to publish a platform in which it criticized the environmental and gay rights policies of its own nation, but then went out of its way to single out only the Black nation from among all the other polluters and homophobic countries of the world?

Would anyone hesitate to describe the singling out of the world’s only Black nation for unique condemnation as an act of bigotry, motivated by anti-Black racism? If that is the case, how is it different when Black Lives Matter singles out the only nation state of the Jewish people for unique and undeserved condemnation? Is not the application of a double standard based on religion as bad as a double standard based on race?

Criticizing Israel for its imperfections is not only fair, it is desirable. But only when it is based on a single standard of comparison with other nations of the world. Condemning the nation state of the Jewish people alone, in a world with far greater offenders, cannot be justified by any moral principle. It is antisemitic, pure and simple. And the Black Lives Matter platform is guilty of the serious sin and crime of antisemitism.

Unless Black Lives Matter explicitly rescinds its antisemitic platform, the organization should not receive the support of decent people. That would be a tragedy because Black Lives Matter does so much good. But throughout history organizations that did good also promoted racism, antisemitism, homophobia and other forms of bigotry. Their good deeds do not excuse or justify their bad ones.

Today more than ever we should recognize that there must be zero tolerance for any form of bigotry, including antisemitism, even if it is engaged in by organizations and people who otherwise do much good. The movement to tear down the statues of people like Thomas Jefferson, George Washington, Andrew Jackson, Columbus and even Abraham Lincoln, because they also engaged in bigoted actions and promoted bigoted ideas, should teach us that we cannot condone bigotry by today’s do-gooders. Rescinding the bigoted portions of the Black Lives Matter platform is mandated by the morality of those who would cancel the contributions of past leaders because of their imperfections. Here we have an opportunity to act now, to prevent bigotry from spreading today.

I once again challenge the leaders of Black Lives Matter to rescind their antisemitic and false condemnation of the nation state of the Jewish people. If they refuse, then those of us who care deeply about Black lives, but also care deeply about ending the scourge of antisemitism, must support organizations other than Black Lives Matter that promote racial justice — without also promoting antisemitism.

Alan M. Dershowitz is the Felix Frankfurter Professor of Law Emeritus at Harvard Law School. Follow him on Twitter @AlanDersh and on Facebook @AlanMDershowitz.

This was originally published in Algemeiner.