I really don’t think FreeRepublic is the place for Christian-Jewish dialog of this sort.
Orthodox Jewish people and fundamentalist Christians have a lot in common socially, politically, and even in love of G-d, but there are intractable theological differences, and it serves no reason to bring it up.
Yes, Christians think Jewish people are going to Hell. That’s fine, and most Orthodox Jewish people appreciate the concern for their eternal well being.
On the topic, I think the “cult” slur is novel, and the result of inexact typing, so I don’t take that as an insult.
Now, Reform folks DO think Orthodox and Lubavitchers, in particular, are a cult. If this was coming from them, I accept what they say as an intended insult.