Yet another apparent anti-Semitic multiple murder has hit the United States with Tuesday’s killing of four people and the subsequent deaths of the two attackers in a Jersey City, N.J. The New York Times , New York Post and other outlets reported Wednesday that the slaughter appears to be linked to a black supremacist doctrine.

Mayor Steven Fulop had already said that the kosher grocery store where most of the shooting took place was intentionally singled out by the killers, suggesting a terrorist attack that specifically targeted Jews. Now law enforcement official say at least one of assailants had posted anti-Semitic comments online, and was or had been a Black Hebrew Israelite.

If so, it is the latest, and by far the most violent, incident to bring a little-known doctrine that is an outgrowth of early black nationalist thinking to widespread public attention. While people affiliated with the movement had been in the news recently for triggering the Covington students’ apparent confrontation with a native American drummer in D.C. and for walking into the Bronx Zoo’s lion enclosure, the best-known previous atrocity connected to the bizarre theology was the murder, in the late 1980s, of 14 people by killers linked closely to the South Florida-based Nation of Yahweh. The Nation’s leader, Yahweh ben Yahweh, died in 2007 after serving 11 years of a federal prison sentence for racketeering and conspiracy. The severed ears of several of the white victims were reportedly brought to Yahweh ben Yahweh as trophies.

The United States and much of the rest of the world has seen a remarkable uptick in anti-Semitic propaganda and violence, especially since the 2017 march in Charlottesville, Va., where white nationalist chanted “Jews will not replace us.” The Anti-Defamation League recently reported a “historically high” number of anti-Semitic incidents in the last several years, and there have been deadly attacks in that period on synagogues in Poway, Calif., and Pittsburgh, where 11 died. In addition, anti-Semitism is clearly growing in countries like Hungary and Poland, and even the British Labour Party under Jeremy Corbyn has been implicated.

But political violence from black anti-Semites has been the exception, with the vast majority of such attacks coming from white nationalists. While it is true that surveys have shown higher levels of anti-Semitism among African Americans than white Americans, those attitudes have not generally led to terrorism.

Black Hebrew Israelism has roots in Black Judaism, which was a generally non-racist theology that emerged in the late 19 th century and was one variant of developing black nationalist ideas. Its basic belief is that American blacks are the real descendants of the Hebrews of the Old Testament, and that those who today call themselves Jews are lying about being the Bible’s chosen people. Many followers believe that whites and Jews will soon be either killed or enslaved as payback from God for their role in enslaving Africans in the Americas.

Although there is no central authority of Black Hebrew Israelism, as it is practiced in small disparate groups in many of the nation’s largest cities, most of the so-called Israelites see Jews as biblical imposters and the primary facilitators of so-called cultural “filth,” such as Hollywood movies. They also describe Jews as self-interested moneymakers and particular enemies of black Americans.

Perhaps the most bizarre thing about Black Hebrew Israelism is the way it mirrors, with only a change in color, the ideas of Christian Identity. Identity is an important white supremacist theology practiced in many Klan groups, along with other entities like the once-important Aryan Nations. Its hardline version describes Jews as the offspring of a literal sexual union between Eve and the Serpent in the Garden of Eden, always at work on behalf of their progenitor, Satan.

Black Hebrew Israelism is not the only strand of organized black anti-Semitism in America. The largest black hate group, the Nation of Islam, does not traffic in bible stories but it is heavily anti-Semitic, with its leaders offering a string of vicious comments about Jews along with falsely accusing them of being the primary purveyors of the transatlantic slave trade.

Bizarrely, the Jersey attack came the same day it was reported that President Trump was expected to sign an executive order that effectively treats Jews as a “nationality” rather than a religious group — despite the undisputed fact that Jews are not a single ethnicity. The vast majority of Jews, for instance, accept that Ethiopian Jews, who are black, are in fact Jewish.

Many conservative Jews applauded the idea, which would allow the federal government to withhold money from college campuses that fail to adequately combat anti-Semitic discrimination. The move is seen primarily as a way to take on the so-called Boycott, Divestment and Sanctions movement, which many Israel supporters view as fundamentally anti-Semitic.

But many liberal American Jewish groups have responded negatively to the idea, suggesting that it is an attempt to stifle criticism of Israel and support for the Palestinians. The Washington Post quoted Jeremy Ben-Ami, the president of J Street, saying it was meant to have a “chilling effect on free speech and to crack down on campus critics of Israel.” Another group, IfNotNow, said it was “bigoted” for playing into ancient stereotypes of Jews belonging to a kind of tribal nation, and thus promoting the “dual loyalty” charge.

Trump has pushed similar ideas. In August, he accused Jewish Democrats of being “disloyal to the Jewish people… and very disloyal to Israel.” He has echoed common tropes about Jews being primarily concerned with money. In 2016, he Tweeted an image of Hillary Clinton sitting atop a pile of money with a superimposed Star of David.

Black Hebrew Israelites, who may number in the thousands but are clearly not a dominant strand of African American thinking, may be the latest entrants into the world of anti-Semites willing to engage in political violence. But they are only the latest, as white nationalists, political leaders here and abroad, and any number of others take up the hatreds once thought to have died in World War II.