When Marcion of Sinope (85-160 CE) argued that the Christian Bible should include his own modified version of the New Testament but nothing of the Old, and, furthermore, that the God of the Hebrew Bible was not the God worshipped by Christianity’s founders, he was excommunicated by the early church. Yet, argues Brad East, his ideas have continually resurfaced in Christian thought, especially among those who embrace an extreme version of supersessionism—the idea that God has rejected the Jews as his chosen people, and replaced them entirely with the Christian church:

Marcion [has given] his name to that most reliable of Gentile sins: distaste for the ways and works of the God of the Jews—a distaste more of the gut than of the mind, a reflexive revulsion that invariably encompasses both the God of the Jews and the people whose God He is. . . . In its rejection of Marcionism, the church staked a claim to this principle: the only God with whom it would have to do was the Jewish God. . . . But the church’s consistency in maintaining this principle was uneven at best. The specter of Marcion continued to haunt Europe. . . . .

Protestants and Catholics have tended to harbor different kinds of antagonism toward Jews. Protestantism thrives on its own supersessionist narrative, according to which the faithful reformers of the 16th century are analogous to the apostles in the first, overcoming the legalistic conventions and authoritarianism embodied, respectively, in the Roman papacy and the Jewish Pharisees. In this narrative, Catholics are neo-Judaizers; stiff-necked Israelites are proto-Catholics. . . .

Over the years, Protestantism’s leading lights increasingly defined Christianity against the Jews. . . . What [Enlightenment-influenced Protestant thinkers like] Kant and his heirs wanted, ultimately, was God without the Jews. They wanted a God unbound to one people among all others. A God who had not picked Abraham out of the crowd and promised divine presence and blessing to his lineage for all time. A universal God, a God of all lands and not the land, a God revealed in all traditions and not just this one. A God revealed in humans, yes, but not incarnate in this one alone, the Galilean [Jesus]. . . .

[By contrast], while Catholicism may lack the revolutionary-supersessionist gene of Protestantism, its deepest historical challenge to the Jews is political. Usury laws entrapped Jewish merchants in a vicious Catch-22; havens of refuge become ostracizing ghettoes. . . . Marcionism [remains] a demon that has yet to be exorcised. Indeed, rising levels of anti-Semitism in the West suggest a tragically short historical memory.