On Sunday, to mark the first anniversary of the Oct. 7 Hamas massacre in Israel, thousands of demonstrators massed in downtown Boston to call for more deadly violence against Jews, not just in Israel but everywhere.

“On Storrow Drive,” the Boston Globe reported, “the demonstrators chanted ‘intifada, intifada, globalize the intifada.’ ” An intifada is a terrorist uprising. During the Palestinian intifada launched by Yasser Arafat in 2000, more than 1,000 Israeli Jews were killed, and thousands more maimed, through bus bombings, drive-by shootings, rocket attacks, and lynchings. The meaning of “globalize the intifada” is not an enigma: It is an exhortation to terrorize and kill Jews wherever they live, which is why the phrase is popular with so many of those who applaud or justify the slaughter, rape, and kidnapping of Oct. 7, 2023.

In the weeks that followed that terrible day, I often heard it said that for American Jews, everything had changed. A year on, I think it is more accurate to say that Oct. 7 finally made it clear that nothing had changed. The conviction that America was fundamentally different, that it couldn’t happen here, has been toppled. Even in America, which millions of Jewish immigrants from Eastern Europe extolled as a “golden land” because it offered haven from antisemitic persecution, we know now that there is no permanent escape from the hatred that has accompanied the Jews through their long, long history.

In a beautiful letter to the Jewish community of Newport, R.I., in 1790, the nation’s first president promised that the United States would give to “bigotry no sanction.” In America, unlike the Old World, Jews would “merit and enjoy the good will of the other Inhabitants; while every one shall sit in safety under his own vine and fig tree, and there shall be none to make him afraid.”

In the America I grew up in, it was possible to believe that George Washington’s faith in America’s acceptance of Jews had been permanently realized and was so deeply embedded in the fabric of American life that nothing could shred it. That was the view of leading Jewish thinkers. In a 1997 book, Alan Dershowitz expressed confidence that “institutional antisemitism is on its last legs” and that “today’s Jew-haters are largely marginalized and powerless.” A few years later, in a New Republic essay headlined “Hitler Is Dead,” Leon Wieseltier rebuked American Jews who worried about antisemitism for giving way to “ethnic panic.”

Even before last Oct. 7, it had become clear that the old poison was beginning to spread. Antisemites opened fire on synagogues, Jewish community centers, and kosher markets. They chanted “Jews will not replace us” in Charlottesville, Va. They desecrated Jewish cemeteries and stabbed rabbis and vandalized Holocaust memorials. They used their positions in Congress to demonize Jews. They ostracized Jewish college students for supporting Israel and used their massive social media followings to promote Holocaust denial.

For all that, the reaction to Oct. 7 came as a shock so severe that many American Jews are still struggling to process it. The savagery of the terrorists’ attack, unspeakable though it was, was not unlike other terrorist horrors, especially those committed by Al Qaeda and Islamic State. But the eruption of fierce support for Hamas in so many quarters in America — I don’t know anyone, even among people who are far from naive about antisemitism, who saw that coming.

As Bari Weiss wrote in The Free Press: “We expected Hamas to kill Jews. We didn’t expect Americans to celebrate it.”

Those of us who follow developments in the Middle East and in Jewish American life could have predicted that Israel’s response to the Oct. 7 pogrom, whatever form it might take, would be denounced by the usual suspects who always denounce Israel. But that 34 student organizations at Harvard would issue a public statement holding Israel “entirely responsible” for the massacre while the bodies of the victims were still warm? That tenured professors at Ivy League universities would exult about how “awesome” and “exhilarating” the bloodbath was? That feminist organizations would refuse to raise their voices against the rape and sexual torture committed against Israeli women and girls? That two-thirds of 18- to 25-year-olds would describe Jews as “oppressors”? That people would claim — on social media, in protests, at public hearings — that the atrocities of Oct. 7 never happened? That when flyers were posted in many American cities showing the names and faces of the hundreds of men, women, children, and even babies kidnapped by Hamas, they would be swiftly ripped down or defaced? That the number of reported antisemitic incidents in the year since Oct. 7 would triple to more than 10,000, including scores of violent assaults and more than 1,800 acts of vandalism?

I wouldn’t have predicted any of that. Perhaps I should have.

Antisemitism always reflects disorder in society. Franklin Foer, writing in The Atlantic in April, observed that “America’s ascendant political movements — MAGA on one side, the illiberal left on the other” — have increasingly come to “regard concepts such as tolerance, fairness, meritocracy, and cosmopolitanism as pernicious shams.” In such an environment, Jews are always at risk.

An inescapable lesson of Jewish history is that golden ages end. After the Holocaust, Americans recoiled from the casual antisemitism that had once been common, and what followed for Jews was an age of safety, tolerance, and even affection to a degree unprecedented over the millennia.

We should have remembered that it was never fated to last. Now we have been reminded.