Interesting in this context is completely divorced from morally good/bad. Could be any group from any area at any time in history. I’ll start with a few, followers of the cult of pythagoras, contemporary black Hebrew Israelites, antiracist skinheads and the Amish (neo-luddites in general). Don’t be racist or a prick to other people discussing.
I’ve always found puritanical groups quite interesting. They seem to evolve out of any subculture be it religious or not. Take the ‘straight edge’ culture, a group of hardcore punk kids who rebelled against the excesses of the punk underground and swear an oath against drinking, drugs and casual sex.
On the religious front you have groups like the shakers. An offshoot of the quakers whose utopian vision prohibited all sex. As a consequence the movement all but died out as they couldn’t reproduce to create new members!
I’ve changed my mind - I just remembered The ‘Zizians’ cult. They are absolutely the strangest group I’ve ever heard about.
https://youtu.be/9mJAerUL-7w
Oh hey I just finished part 2 of the BtB episodes about them
EDIT: lol that’s part 1 you linked to, I assumed it was Strange Aeons
I think the Bruderhof people are the most authentic Christians in the modern world. They are communist (live in community without personal property) and are a cult of Christ.