I would expect the potential commentariat at Less Wrong to be terribly small if anyone holding a firm belief that is not rationally justifiable were banned.

I am highly skeptical that I have fully purged myself of all beliefs where I have been presented with correct damning evidence against them. If anything, reading here has raised my estimate of how many such beliefs I might hold. Even as I purge many false propositions, I become aware of more biases to which I am demonstrably subject. Can anyone here who is aware of the limitations of our mental hardware say otherwise?

I am not as convinced as most posters here that all possible versions of theism are utterly wrong and deserve to be accorded effectively zero probability, but in any case, it's clear that LW (and OB) communities generally wish to consider the case against theism closed. To the extent that the posters do not attack theism or theists in an obviously biased way, I have respected the decision and post and vote accordingly, including downvoting people who try to reopen the argument in inappropriate places.

I also intend to make a habit of downvoting those who waste time denouncing theism in inappropriate contexts or for specious reasons having more to do with signaling tribal bonds than with bringing up any new substantive argument against theism.

I don't recall who suggested that we need another canonical example of irrationality, but I agree wholeheartedly. In fact, I'd suggest we need a decent short list to rotate through, so that no one topic gets beaten up so consistently as to encourage an affective death spiral around it.

I would rather emphasize Raising the Sanity Waterline. If we bar theists outright, we miss the opportunity to discuss rationality with them in different contexts. We don't get to learn what insights they might have when their biases are not in the way. We don't get to teach them about all the biases using nonreligious examples, so that they might, on their own, figure out to check for those same biases in their theistic beliefs. If we allow theists, we still have the karma system to bury any obnoxious comments they make on discussions of religion, and the same karma system will encourage them to participate in the areas where they will get the most benifet.

speaking globally, one cannot be a rationalist of any quality and exempt some assertion from the standards of rationality.

You can't speak globally when it comes to the human brain.

Sure, if brains had any sort of global consistency or perfect internal software reuse, you could say that being a rationalist rules out believing in irrational things.

But as a practical matter, you can't insist on consistency when someone might simply not have thought of applying the same logic to all their beliefs... especially since MOST of the beliefs we have are not perceptible as beliefs in the first place. (They just seem like "reality".)

In addition, our brains are quite capable of believing in contradictory things at the same time, with one set controlling discourse and the other controlling behavior. In work with myself and others who have no conscious religious beliefs, I've often discovered, mid-mindhack, that there's some sort of behavior in the person being driven by an unconscious desire to go to heaven or not be sent to hell. So even someone who thinks they're an atheist can believe in silly things, without even knowing it.

So, IMO, it makes as much sense to ban people with supernatural beliefs, as it does to ban people who have idiotic beliefs about brains being consistent.

Actually, come to think of it, the belief that people's brains must be consistent IS a supernatural belief, as there's no physical mechanism in the brain that allows O(1) updating of belief structures that don't share common components. To insist that the moment one becomes a rationalist, one must then become an atheist, is to insist on a miracle inconsistent with physics, biology, and information science.

So, if we are going to exclude people with inconsistent or supernatural beliefs, let's start with the people who insist that the brain must be supernaturally consistent. (This is actually pretty reasonable, since such an error in thinking arises from the same mind-projection machinery that gives rise to theism, after all...)

Are you so confident in your perfect, unerring rationality that you'll consider that particular proposition completely settled and beyond questioning? I'm about as certain that there is no God as one can get, but that certainty is still less than 100%, as it is for virtually all things I believe or know. Part of maintaining a rational outlook toward life, I'd think, would be keeping an attitude of lingering doubt about even your most cherished and long-held beliefs.

Really must set up my LessWrong dev environment so I can add a patch to show both upvotes and downvotes!

Indeed. If that is the only change to this site's system or ethic that comes out of this discussion, it will have been worth it.

Not sure I disagree with your position, but I voted down because simply stating that your opponent is wrong doesn't seem adequate.

There are different standards for what to consider sane. At least among ourselves, we should raise the sanity waterline. But as the word is normally used, informed and rational theists are considered possible.

I would like you to elaborate more. I gave an argument in favor of being a theist. I have seen few good ones in favor of being an atheist.

I'm not at all convinced that atheism is the best epistemic position (most epistemically rational). I'm an atheist for purely methodological reasons, since I'm a philosopher, and dead dogma is dangerous. I could see someone being a theist for purely instrumental reasons, or by default since it's not a very important question.

I am frankly amazed that so simple and evident an assertion should receive so many negative votes. (Not surprised, merely amazed. It would have to violate my expectations to be a surprise.)

Can I assert that Santa Claus does not exist and cannot be rationally considered to exist without receiving similar votes, or do I need to review the demonstration of why such is the case to avoid the wrath of the voters?

A more pertinent question: why should any of us care about negative votes when they're given out so poorly?