Leaders are useful.

Leaders cause people to lapse into thinking "The Guru has an answer, even if I don't understand it". This is aready happening in LW.

I'm not really sure how the sequences map onto the Christian Gospel

People say "The answer is in the Sequencess" without bothering to check that it is.

,Assuming we don't excommunicate people for disagreeing it (politely), I'm not sure why not. I mean, we mostly agree that there's no God, for example; rationality should, presumably, move us closer to the correct position, and if most of us agree that we've probably found it, why shouldn't we assume members agree unless they indicate otherwise?

Rationalists should think and argue. However LWers just say "this is wrong" and downvote.

Because meeting people with similar interests and goals is only done via religion.

Other ratioanlists manage withoiut them. LWers aren't aware of how religious they seem.

Because any idea that predicts the end of the world must be discarded a priori?

Because it fools people into thinking they are Saving the World This sense of self-importance is yet another mind killer. Instead of examining ideas dispassionaely,a s they should, they develop a mentality of "No, don't take my important world-saving role away from me! I cannot tolerate any criticism of these ideas, because then I will go back to being an ordinary person".

Because any idea you place in the reference class "god" must be discarded a priori?

See above. Leads to over-estimation of individual importance, and therefore emotional investment, and therefore mind-killing.

An excellent suggestion! In theory, we already do (we could probably do better on this.)

I'll say

Trolling, however, is not generally considered part of that.

"Trolling" is the blind dogmatist's term for reasoned criticism.

I> 'm not even going to bother linking to the appropriate truism, but reversed stupidity etc.

Stupidity is stupidity, too.