Sorry, I missed your joke on first read.
I get it now.
Still, I think every cult is harmful in some way.
Well, Steeler fans for example. Harmless lately except to people in Cleveland. Bowlers. And if you don't think bowlers are a cult, I'd like you to meet my mother-in-law...
But seriously, I would challenge you to find any cult more dangerous than Karl Marx's. In the twentieth century they were responsible for more murder, torture, and oppression than all other causes combined. And considering how bloody that century was, that's really quite an accomplishment. By comparison, I'd say nearly all other cults were harmless, indeed. Made all the more harmful because their only serious competition--the fascists, a distant second--are universally reviled. We have this problem with this Leftist cult you see, it still has its adherents.