I think it's perniciously bound in the European experience of 'other'. The history of Europe is a tldr, but when it's supreme religion courted with anti-semitic tropes as part of its own foundational messianic story and when a Jewish diaspora was the most common form of strictly embedded 'other' that could be engaged with (distinct from the social and military interaction with Muslims/Moors etc) within Europe, anti-Semitism becomes sadly self evident.
I think this is on to something. Antisemitism at heart is rooted in a fear/hatred of the Other, but specifically the Other
who lives among us. The uniqueness of the Jewish experience in medieval, early modern and modern Europe was that of a people that was distinctly its own and held strong to its cultural distinctiveness, yet at the same time tried its best to make it home wherever it could. There is something about this dynamic that appears uniquely threatening to humanity's most tribalistic instincts, and I think that explains at least part of the uniquely unhinged reaction. Religion for a long time was the main cover for it (even then it was always just a cover) until scientific racism came along and suddenly people had a lot of very rational sounding reasons why Jews deserved all the hate, but fundamentally those are all justifying mechanisms.
Another aspect might be Jewish culture's emphasis on learning and scholarship, which created a natural link between anti-intellectualism (always a favorite of authoritarian personalities) and antisemitism. And with it, the development of a strong secular Jewish culture starting in the 18th century that did have considerable influence over and cultural intermixing with Europe's gentile secular culture (arguably the closest thing we've had to a "Judeo-Christian" cultural phenomenon, and it was an explicit rejection of both Jewish and Christian religious orthodoxy!). For reactionaries of all stripes, this was of course a massive threat, and Jews became a convenient scapegoat for the rise of "subversive" ideas like liberalism and socialism.
There's a lot more to be said about this, but I can tell I'm rambling and that's probably because I'm seriously down with the flu, so I'll just leave it there for now.