Three years have passed since the Hamas massacre of Oct. 7, 2023 — the wholesale murder, rape and torture of more than 1,200 men, women, children and infants in Israel. Yet as Jews everywhere gather to mourn, what should be a day of quiet reflection and prayer, of defiant cries of “Never again,” is being eclipsed by something dark and obscene. The tragedy of 10/7 has ripped the veil off the antisemitism that has always bubbled below the surface. As the nation of Israel dares to defend itself against an existential threat, the gloves have come off. Jew hatred is...