This week’s Torah reading of Ki Teytsey concludes with a command never to forget the nefarious deeds of the Amalekites—who attacked the Israelites from behind as they were coming out of Egypt—and to “blot out the memory of Amalek from underneath the heavens.” By contrast, the same Torah reading also commands, “Do not despise an Egyptian, because you were strangers in his land.” Why, asks Jonathan Sacks, are the Amalekites so singled out? After all, the Egyptians enslaved the Israelites for centuries, and attempted genocide by the slaying of the male children. Sacks finds the answer in the Talmud’s teaching that only love that is not dependent on any one specific thing can endure:

The same applies to hate. When hate is rational, based on some fear or disapproval that—justified or not—has some logic to it, then it can be reasoned with and brought to an end. But unconditional, irrational hatred cannot be reasoned with. There is nothing one can do to address it and end it. It persists.

That was the difference between the Amalekites and the Egyptians. The Egyptians’ hatred and fear of the Israelites were not irrational. . . . The Egyptians [as the book of Exodus states] feared the Israelites because they were numerous. They constituted a potential threat to the native population. . . . (Note that there is a difference between “rational” and “justified.” The Egyptians’ fear was in this case certainly unjustified.)

Precisely the opposite was true of the Amalekites. They attacked the Israelites when they were “weary and weak.” They focused their assault on those who were “lagging behind.” Those who are weak and lagging behind pose no danger. This was irrational, groundless hate.

With rational hate it is possible to reason. . . . But with irrational hate it is impossible to reason. It has no cause, no logic. Therefore it may never go away. Irrational hate is as durable and persistent as irrational love. The hatred symbolized by Amalek lasts “for all generations.” All one can do is to remember and not forget, to be constantly vigilant, and to fight it whenever and wherever it appears. . . .

Anti-Semitism . . . is the paradigm case of irrational hatred. In the Middle Ages Jews were accused of poisoning wells, spreading the plague, and in one of the most absurd claims ever—the blood libel—they were suspected of killing Christian children to use their blood to make matzah for Passover. This was self-evidently impossible, but that did not stop people from believing it.

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.