Question about Lubavich Hasidim

As I understand it, this branch of Hasidim consider Rebbe Menachem Schneerson to be the Messiah (forgive me if this is no longer the case; I left Brooklyn 20 years ago). Would this cause mainstream Jews to no longer consider them to be Jewish? They do not consider so-called Jews for Jesus to be Jewish (correctly, in my opinion); would the same apply to another “false Messiah”?

What is a “mainstream Jew” anyway?

My understanding is that Jewishness is not a matter of what you believe or what you practice. That would be Judaism. I’m going to guess that it completely depends on the branch, what opinion they have of Lubavich Hasidism. So you’d have to be a lot more specific.

To be more specific, the four major branches (Orthodox, Conservative, Reconstructionist, Reformed).

AIUI, the Chabad-Lubavitcher leadership have officially repudiated Schneerson-focused messianism:

And yes, as that article describes, some other Jews have compared those messianic beliefs to Christianity.

Two jews; three opinions. We are a remarkably disputatious lot.

Or, as the late Rabbi Schach, the undisputed leader of the Misnagdim Orthodox (the Orthodox are roughly split into Hassidim and Misnagdim) said: "The Lubavitcher are the (non-jewish) sect closest to Judaism.

It’s a minority of Chabad chasidim that believe this way, but a very vocal minority. Much of the Chabad community in Israel have this belief.

Reform

Never “Reformed”

Sorry, I knew that.

According to my Rabbi (I don’t know if this opinion is widely held or not) such a belief is foolish but not heretical.