Earlier quoted context omitted.
It's basically a secular religion. Substitute God with AI or the concept of rationality and use "first principles"/Bayesianism in an extremely dogmatic manner similar to Catechism and you have the Rationalist/AI Alignment/Effective Altruist movement. Ironically, this is how plenty of religious movements started off - basically as formalizations of philosophy and ethics that fused with what is basically lore and world…
This complaint seems to amount to "They believe something is very important, just like religious people do, therefore they're basically a religion". Which feels to me like rather too broad a notion of "religion".
Whenever I try to get an answer of HOW (as in the attack path), I keep getting a deus ex machina. Reverting to a deus ex machina in a self purported Rationalist movement is inherently irrational. And that's where I feel the crux of the issue is - it's called a "Rationalist" movement, but rationalism (as in the process of synthesizing information using a heuristic) is secondary to the overarching theme of techno-millenarianism.
This is why I feel rationalism is for all intents and purposes a "secular religion" - it's used by people to scratch an itch that religion often was used as well, and the same Judeo-Christian tropes are basically adopted in an obfuscated manner. Unsurprisingly, Eliezer Yudkowsky is an ex-talmid.
There's nothing wrong with that, but hiding behind the guise of being "rational" is dumb when the core belief is inherently irrational.