I don’t know what the opposite of an antisemite is. But whatever we call those who stand up for the Jewish community, we need more of them now. In 2019, Ibram Kendi published “How to Be an Antiracist,” a guide to recognizing and countering institutionalized racism in America. Today, the world needs a primer on fighting antisemitism. The Jewish community is not panicking, but after years of rising Jew-hatred around the globe, an escalation predating Oct. 7, 2023 (though Hamas’ assault and Israel’s response surely exacerbated it), the massacre in Sydney shook us to our core. We Jews now understand...