Many folk here on LW take the simulation argument (in its more general forms) seriously. Many others take Singularitarianism1 seriously. Still others take Tegmark cosmology (and related big universe hypotheses) seriously. But then I see them proceed to self-describe as atheist (instead of omnitheist, theist, deist, having a predictive distribution over states of religious belief, et cetera), and many tend to be overtly dismissive of theism. Is this signalling cultural affiliation, an attempt to communicate a point estimate, or what?
I am especially confused that the theism/atheism debate is considered a closed question on Less Wrong. Eliezer's reformulations of the Problem of Evil in terms of Fun Theory provided a fresh look at theodicy, but I do not find those arguments conclusive. A look at Luke Muehlhauser's blog surprised me; the arguments against theism are just not nearly as convincing as I'd been brought up to believe2, nor nearly convincing enough to cause what I saw as massive overconfidence on the part of most atheists, aspiring rationalists or no.
It may be that theism is in the class of hypotheses that we have yet to develop a strong enough practice of rationality to handle, even if the hypothesis has non-negligible probability given our best understanding of the evidence. We are becoming adept at wielding Occam's razor, but it may be that we are still too foolhardy to wield Solomonoff's lightsaber Tegmark's Black Blade of Disaster without chopping off our own arm. The literature on cognitive biases gives us every reason to believe we are poorly equipped to reason about infinite cosmology, decision theory, the motives of superintelligences, or our place in the universe.
Due to these considerations, it is unclear if we should go ahead doing the equivalent of philosoraptorizing amidst these poorly asked questions so far outside the realm of science. This is not the sort of domain where one should tread if one is feeling insecure in one's sanity, and it is possible that no one should tread here. Human philosophers are probably not as good at philosophy as hypothetical Friendly AI philosophers (though we've seen in the cases of decision theory and utility functions that not everything can be left for the AI to solve). I don't want to stress your epistemology too much, since it's not like your immortal soul3 matters very much. Does it?
Added: By theism I do not mean the hypothesis that Jehovah created the universe. (Well, mostly.) I am talking about the possibility of agenty processes in general creating this universe, as opposed to impersonal math-like processes like cosmological natural selection.
Added: The answer to the question raised by the post is "Yes, theism is wrong, and we don't have good words for the thing that looks a lot like theism but has less unfortunate connotations, but we do know that calling it theism would be stupid." As to whether this universe gets most of its reality fluid from agenty creators... perhaps we will come back to that argument on a day with less distracting terminology on the table.
1 Of either the 'AI-go-FOOM' or 'someday we'll be able to do lots of brain emulations' variety.
2 I was never a theist, and only recently began to question some old assumptions about the likelihood of various Creators. This perhaps either lends credibility to my interest, or lends credibility to the idea that I'm insane.
3 Or the set of things that would have been translated to Archimedes by the Chronophone as the equivalent of an immortal soul (id est, whatever concept ends up being actually significant).
You're making good points, with which I largely agree, with some reservations (see below). I'd just point out that this wasn't the argument Komponisto was making - he was talking only about relatedness in the ancestry sense.
Your list of attributes is probably good enough to distinguish e.g. a simulation argument from "religions" and justify not calling it one. There are two difficulties, however. One is that adherence to these attributes isn't nearly as uniform among religions as it's often rhetorically assumed on LW to be. There's a tendency to: start talking about theism; assume in your argument that you're dealing with something like an omnipresent, omniscient monotheistic God of Judaism/Christianity whose believers are all Bible literalists; draw the desired conclusion and henceforth consider it applying to "theism" or "religion" in general. I find this fallacious tendency to be frequent in discussions of theism on LW. This comment from the earlier discussion is relevant, as are some other comments there. In this post, Eliezer comments that believing in simulation/the Matrix means you're believing in powerful aliens, not deities. Well, consider ancient Greek gods; they are not omniscient, not omnipresent, they can die... they're not more powerful than the simulation runners, and arguably not very ontologically different; are they not deities, but aliens? Was that not religion? [1]
It's kind of understandable that one thinks of the concept of God and Jehovah pops into view. But if you stick with Jehovah - and not even any Jehovah, but a particular, highly literally interpreted kind - it's no good pretending afterwards that you've dealt a blow to religion or to theism.
So proper account of what religions are actually out there makes your list of attribute much less universal, and the dividing line between religions and something like BTanism much less sharp. But, to be clear, I still think this line can be usefully drawn.
The second difficulty is something I've already written to Komponisto above: OK, it's not a religion, so what? The really important thing is whether it's like a religion in those things that ought to make a rationalist not glibly and gleefully dismiss one if they're psyched about another. And among those things worship and sacred texts are arguably less important than e.g. falsifiability. Have you seen a good way to falsify a simulation claim recently?
[1] I just remembered that Dan Simmons develops this theme in Ilium/Olympos. The second book is much worse than the first one.
The Greek gods were, in fact, immortal. Other gods could wound or imprison them, but they couldn't be killed. The Norse gods, on the other hand, could indeed die, and were fated to be destroyed in the Ragnarok.