In 1391, in the wake of a wave of bloody pogroms that swept Spain, Profayt Duran, along with tens of thousands of other Jews, was baptized a Christian. Privately, however, he continued to write treatises on Hebrew grammar and the Jewish calendar and to polemicize vigorously against Christianity. Reviewing Maud Kozodoy’s The Secret Faith of Maestre Honoratus, the first full-length biography of Duran, Frederic Raphael writes:

Before his conversion, Duran had prospered professionally as sage, physician, astrologer, and mathematician. Though excluded from the universities, Jews could find favor at court. Diplomatic doctors moved freely in Christian Spain. . . . As well as being guardians of Jewish science, philosophy, and literary culture, successful medical men, once rich, often became moneylenders.

Duran’s case is particularly fascinating because he was impelled publicly to embrace a religion he continued to scorn in private essay-letters. Secretly, Duran confessed his agony over the dichotomy in which “inner orientation cannot correspond to outward practice.” . . . As a converso, Duran may have guarded his tongue, but he was covertly outspoken with his pen.

[As a Jewish rationalist], Duran accepted the . . . “stark [Maimonidean] dichotomy between reason and revelation.” The distinction left science free to be “grounded in an assumption of the fundamental validity of rational thought.” Jewish religious belief neither muzzled scientific discovery nor tortured logic. . . . Duran saw that science set standards against which Christian dogma, transubstantiation in particular, could be anatomized.

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.