It’s not a hergesh. The Rebbe said he was moshiach in his basi legani due to being the 7th Rebbe, then dropped hints about it for years, and the gullible ones believed it.
You are believing exactly what you are brainwashed to believe.
It’s kinda funny to see a group go nuts over the 12th ikkar but make a cholent out of every other ikkar by calling it “chassidus”. Hashem has no guf? Well chassidus so atzmus. Only Hashem runs the world? Well atzmus so tzaddik gozer so the Rebbe runs the world. You can only daven to Hashem? Well atzmus so you can daven to the Rebbe. Moshe was the biggest navi? Well the Rebbe is the ispashtusa demoshe and even bigger than Moshe because the Rebbe can’t make mistakes. Oh and thanks to atzmus everything the Rebbe touches had elokus.
All you need to do is substitute “eigel” for “Rebbe” for leitznusa deavoda zara. Whereas in Crown Heights they say “der Rebbe vet helfn” just say “der eigel vet helfn”. etc etc