decentralized cult which worships the concept of rational thinking as superior to evidence. has lots of little rituals which are supposed to invoke rational thinking. uses AI in the place of angels and demons. no core holy texts, but the closest things are a sequence of blog posts and a harry potter fanfic. very influential in silicon valley, very intermingled with various explicitly fascist groups

Longer than I'd intend, but the way I describe it is probably as

1. A mystical Harry Potter based sex cult deeply embedded in the techbro scene. They want what many cults want: to commune with God, achieve immortality or enlightenment, and obtain power in the current world, but they dress it in the trappings of science and computer programming.

2. Do to demographic features, their desire to be clever, and a certain contrarian attitude, they will often seek to rationalise harmful social practices, which leads them to support anti-feminist and race realist positions with shocking frequency.

3. Because of their close connections to the tech scene, along with the personal relationship the cult founder had with Peter Thiel, and the fact that the cult has been indoctrinating kids since the aughts, they are shockingly influential in the AI scene.

4. As most cults, they claim to want to teach people to think correctly (rationally), but they actually value the community of being in a cult (and the potential social networking and financial benefits) over thinking rationally.

5. In terms of style, they like long works with unclear arguments, being clever or witty over being right, and strongly signalling their rationality (sometimes even using good tools), but not allowing that to interfere with the core features of being a cultist.

(1-3) are what I'd consider core. (4-5) are what I'd add if the person seems interested. If they seem really interested, I'd also discuss other connections (e.g. to Effective Altruism, the Future of Humanity Institute, George Mason University, Future Perfect, neoreaction), their ideology in more specific terms (e.g. the Sequences, Roko's Basilisk), and associated members (e.g. EY, SSC, Aella, SBF).

the problem of my life. I have literally found it easier to explain Scientology than Roko's basilisk.

SV Scientology, they can't land you a leading role in a summer blockbuster but they sure as hell can put you in the running for AI policy related positions of influence or for the board of a company run by one of their more successful groomings. Their current most popular product is court philosophers for the worst kind of aspiring technofeudalist billionaire.

If this gets them interested you'll eventually get your chance to do a deep dive to any details of cosmist lore you find relevant.

It's a little bit like a tiny version of the Mormons if Joseph Smith had read the collected works of Isaac Asimov instead of the Bible and also his name was Yud.

Or to go with less of a sneer, the Rationalist/TESCREAL/Californian Ideology is a loose grouping of fringe beliefs rooted in old-school science/tech fetishism with a lot of science fiction overlays and libertarian/reactionary politics that effectively define "let ultrawealthy tech capitalists do whatever they want" as the only reasonable choice and make it a moral imperative.

Personally I might try explaining some of the foundational stuff before going into the big R. Scientism, utilitarianism would be my starting points.

Techish (I would use the word techbro here, but that needs an explantion even) people who want to make their fictional science fiction utopia real, but got so scared of their own science fiction ideas going wrong and killing everybody they started a cult around rationality, sort of a Vulcans fan club. They have a pattern where they think they and their methods are smarter and better than actual experts.

When trying to do their own research with an open mind, but they left their minds so open that all kinds of sexists and racists crawled in. Who are welcomed as long as they are verbose enough.

And to close it off, Musk is a fan.