Tyrrell, it's not my fault if you can't handle reasoning from hypotheticals, but it certainly doesn't make that form of reasoning -- used in the rest of the civilized world -- off-limits.

Hypotheticals have their uses, but they are easy to abuse. Hypotheticals are usually fine for

making the meaning of a claim clear by putting it in a simpler context (e.g., explaining the physics of a pendulum by imagining that it has an inelastic and frictionless rod), and
constructing counter-examples to absolute claims (e.g., "Stealing is always wrong!" "Really? What about if you washed up on shore after a shipwreck, and you had to steal food immediately or else die of starvation?"

Neither of these apply to your argument. Your claim was already clear, and I'm making no absolute claim. I'm the one claiming that there is inadequate evidence to justify your confidence in your conclusion.

Despite their uses, hypotheticals are usually useless for resolving disagreement. As I've explained, by passing to a new hypothetical situation, you only increase your burden of proof. In addition to proving the original claim, you must now show that the hypothetical doesn't differ significantly from the actual situation. Moreover, in practice, when both participants are intelligent and thoughtful, the hypothetical will almost always fail to capture the heart of the disagreement.

For example, you've said that your claim is "hard to see" and "less obvious" in the case of religion. It shouldn't surprise you to learn that the elements making it hard to see and less obvious are why I doubt your claim. Thus, by moving to a hypothetical where those elements are absent, you fail to address the source of my doubt.

I actually think it's obvious enough why actual beliefs in (certain religions') doctrine of eternal hellfire would logically imply a direct transition to an ascetic lifestyle or other drastic choices, and we can go that route if it keeps things in your comfort zone.

This is a strong claim. I'm skeptical that religious claims are precise and unambiguous enough to logically imply such things. You should be able to give a logically rigorous demonstration of this implication if it is so obvious. I will concede your point if you can do this.

But the point is pretty simple: in the hypothetical, we can quite easily draw conclusions: either a) the person doesn't actual have an internal predictive model of reality including a deadly bed monster, or b) he has some kind of weird psychology.

In short, you go with b) and I go with a). Which is why I think this kvetching about hypotheticals suddenly being off-limit is moot: even when I make the situation "more favorable" to my theory, you just bite a bigger bullet, cutting off whatever implication I would have claimed follows back to the original topic of religion.

You make a fair point, but one to which I have a response. Why did I object to your hypothetical if I reached the same conclusion within it anyway?

Naturally, if you keep adding conditions to your hypothetical, I will eventually agree that, given those conditions, your conclusion follows. But the more conditions you add, the further you take us from the actual situation, and so the less bearing the hypothetical has on the actual situation.

You had not yet added so many conditions to your hypothetical that I agreed with you, but I could already foresee that you eventually would, though it would be pointless for the reason above. Indeed, you added several such conditions below, conditions that were not present in your original formulation.

In particular you added that the person is "not … obviously crazy in any other area of his life" and you add that "his mental model of other phenomena … [is] superior to yours in several areas." That is new information. It is certainly not what I would expect of the actual typical person who claims that there is a killer monster under his bed. Suppose you really did learn of some adult that he earnestly insisted that there was a killer monster under his bed. Prior to further information, wouldn't you expect that this person suffers from numerous other severe delusions?

You've now ruled that out, but only by changing the hypothetical. I'll save you work by repeating that, if you add enough such conditions, I will agree that this individual is probably lying about his beliefs. But that concession will have no bearing on what I think about actual theists.

Now to consider your list of conditions as they pertain to theists:

But note the difficult position you've forced yourself into. You have to believe he is obviously crazy despite:

not being obviously crazy in any other area of his life

Religious beliefs appear to me to spread to other areas of the believer's life in a way consistent with what I'd expect. But I don't expect them to spread as far as you do because I don't see the "obvious" logical implications that you claim above.

the psychological unity of mankind somehow breaking for a huge class of people that have been interbreeding with the rest of humankind and whom no one seriously suggests mandatory psychotherapy

The psychological unity of humankind presents no problem for my hypothesis, because the overwhelming majority of people seem inclined to believe religious claims. It is you and I, natural-born atheists, who are the freaks :). We seem very rare.

his mental model of other phenomena (let's reasonably suppose) being superior to yours in several areas

As I argued above, I would expect evolution to make minds capable of partitioning their beliefs in this way.

his actions associated with these "beliefs" greatly helping him achieve many non-crazy personal goals: having a social network, meeting a compatible spouse, greater assurance of spousal fidelity, the feeling of belonging.

It seems to me that the easiest way to reap all these benefits of belief is to make a mind that can sincerely believe without interfering with important day-to-day conveniences. This would be harder if religion really logically implied asceticism, as you claimed. But I think that the religions we're talking about are designed (by natural memetic selection) to avoid doing that kind of thing.

the similarity (discussed before) between him and the uncountable historical instances of people supposedly going to great lengths for inscrutable theological doctrines, but actually protecting a meme they benefit from.

This presents no particular problem. People often sincerely love their children, but they also often falsely invoke that love as their reason for doing other things, such as going to war, etc.