Last month, at a rally in Michigan for then-congressional candidate Lena Epstein, a self-styled “messianic rabbi” (who was in fact defrocked fifteen years ago by the Union of Messianic Jewish Congregations) delivered a benediction in honor of the victims of the Pittsburgh massacre, offending the sensibilities of many American Jews. David Wolpe explains why the terms “messianic Jew” and “Jew for Jesus” are deliberately misleading, and why the vast majority of Jews are justified in seeing them as outsiders:

According to the strict [talmudic] legal standard, a Jew, no matter what practice or belief he adopts, cannot leave Judaism. But as a communal, practical matter, of course one can. . . . [T]he clear bright line between Jews and Christians is, and has always been, belief in Jesus as divine. It was over precisely this question that early Christians separated from Jews. They were Christians because they accepted Jesus. In the first few centuries of Christianity that conviction split the new religion from its Jewish parent. If you ask why Christians persecuted Jews in the ancient, medieval, and modern period, that is the answer, because they accepted Jesus, and Jews refused to do so. . . .

After thousands of years of understanding this simple difference, in 1970, Moishe Rosen came to the strange realization that tweaking the message of Christianity was a successful strategy and “Jews for Jesus” or “messianic Jews” gained currency. It is a very attractive marketing scheme. You can stay Jewish! No need to abandon the faith of your ancestors. All you need do is make a small adjustment. Of course, that adjustment is precisely what has always divided you, but no matter. Of course, there are no Christians for Muhammad, but no matter. Be a Jew for Jesus, and when Jews object, just disparage their sensitivities.

A “Jew for Jesus” is an insult to Judaism and to Christianity. It takes the central tenet of a faith and pretends that you can hold it without being part of that faith. It is a strategy for conversion, . . . and a transparent one at that, . . . a marketing scheme dressed up as theology, a faith-based oxymoron that no one should believe. . . . [I]t is a disgrace and an offense to the countless Jews who remained faithful in the face of unimaginable suffering and gave their lives for refusing to accept Jesus as their savior.

Two extraordinary events demonstrate something important about Israel’s most fervent adversaries. One was a speech given at something called The People’s Forum (funded generously by Goldman Sachs), which stated, “When the state of Israel is finally destroyed and erased from history, that will be the single most important blow we can give to destroying capitalism and imperialism.”

The suggestion that this tiny state is the linchpin of a global, centuries-old phenomenon like capitalism goes well beyond anything resembling rational criticism. Even if Israel were guilty of genocide, apartheid, and oppression—which of course it is not—it would not follow that its destruction would help end capitalism or imperialism.

The other was an anti-Israel protest that took place in front of New York City’s Memorial Sloan Kettering Cancer Center, deemed “complicit” in Israel’s evils. At organizers’ urging, participants shouted their slogans at kids in the cancer ward, who were watching from the windows. Given Hamas’s indifference toward the lives of Gazan children, such callousness toward non-Palestinian children from Hamas’s Western allies shouldn’t be surprising. The protest—like the abovementioned speech—deliberately conveyed the message that Israel is the ultimate evil and its destruction the ultimate good, cancer patients be damned.

The fact that Israel’s adversaries are almost comically perverse does not mean that they can be dismissed. If its allies fail to understand the obsessive and irrational hatred that it faces, they cannot effectively help it defend itself.