One issue I have with Pascal's wager is that it seems easy to come up with much more extreme religions. 

I believe that in many Christian faiths, when one person is judged as being sent to hell, then afterwards, one person is sent to hell, and experiences the pain that one person can. This might as well last for infinity, but it's still one person's pain.

In comparison, it's easy to imagine a religion that goes much further. Whenever one person is judged as being bad, an infinite number of people will go to hell in their stead (these people might be just like them, if that's important), and these people will be enhanced to experience a greater amount of pain.

Obviously, heaven goes the same way. 1 person experiencing 1-person-unit of heaven-bliss per year, vs. a religion that has infinity people experiencing infinity-person-units of heaven-bliss per year. 

So I'd argue that most religions aren't "Pascal Optimal".

You might say, "Well, there's almost no chance of these pascal optimal religions being true, as no one yet believes in them. We only have the regular religions."

To which the obvious reply is,
"Well, there might be almost no chance, but there is some chance. And when you do the math, doesn't this then check out?"

(If it's not clear, I personally don't believe in either a regularly known religion or a Pascal Optimal religion.)

Thanks for sharing this fun paper!

I think I disagree with several key parts of the argument.

4. Professional philosophers are among the most educated and skeptical people on the planet. Yet,  according to the 2020 PhilPapers survey, 18.83% of them accept or lean toward theism (too low due  to selection effects?). 7.21% were agnostic. If we play it safe and suppose that only a third of the theist  philosophers believe in hell, that’s about 6%. Thus, (on a very conservative estimate) about 6% of the most skeptical people on the planet believe in hell.

I think this makes a pretty important error in reasoning. Grant that philosophers in general are among the most skeptical people on the planet. Then you select a 6% segment of them. The generalization that these are still among the most skeptical people on the planet is erroneous. This 6% could have of (e.g.) average levels of skepticism, and it's the rest of the group that brings up the average level of skepticism of the group.

Here’s Jesus:

“When the Son of Man comes into his glory, and all the angels with him, then he will sit on his  glorious throne. Before him will be gathered all the nations and he will separate people one from another as a shepherd separates the sheep from the goats. And he will place the sheep on his right,  but the goats on the left. Then the King will say to those on his right, “Come you who are blessed  by my Father, inherit the kingdom prepared for you from the foundation of the world. For I was  hungry and you gave me food…

Then he will say to those on his left [the goats], Depart from me you cursed, into the eternal fire prepared  for the devil and his angels. For I was hungry and you gave me no food…Truly, I say to you, as you  did not do it to one of the least of these you did not do it to me. And these will go away into eternal  punishment, but the righteous into eternal life.” (Matt 25:31-46)

This is among the passages commonly interpreted as Jesus discussing hell. However, note that it doesn't actually show Jesus discussing hell as we've been thought to think of it. First, he's clearly speaking in metaphor — he's not talking about literal sheep and goats. It's not clear what the "eternal punishment" he's referring to is. Some people interpret this as more of a "final" punishment, e.g. death, rather than eternal suffering. And indeed, if Jesus were referring to hell as traditionally conceived, I'd expect him to be clearer about this. 

Many scholars on the topic have written extensively about this. My understanding is that there's little solid basis for getting the traditionally understood concept of hell out of the core ancient sources. And I'd expect, if it were true, and Jesus really were communicating about something as important as hell with divine knowledge, there would be no ambiguity about it. (Since the Quran comes after and is influenced by Christian sources, I don't think we should read it as a separate source of evidence.) 

I think this is a very strong reason to doubt the plausibility of hell. And there are many other such reasons:

1. Generally there's little reason to think ancient texts are strong sources of truth on questions of cosmological significance.
2. These kinds of extravagant claims are completely discordant with our ordinary experience of the world.
3. These kinds of claims pattern match to the kinds of stories people might make up in order to control others.
4. There are very plausible error theories about why people believe religious claims like these.
5. There are many religious believers who reject these particular claims about hell even while being sympathetic to other religious claims.

The weight of these considerations drives the plausibility of hell extremely low, much lower in my view than the possibility of x-risk from risks like nuclear weapons, pandemics, AI, or even natural sources like asteroids (which, unlike hell, we know exist and have previously impacted the lives of species).

I think this does make the odds of a religious catastrophe pascalian, and worth rejecting on that basis.

Even if the risk weren't pascalian, I think there's another problem with this argument, with reference to this part of the argument:

Each religion has infinite stakes, so the expected (dis)value of each is equal.

• Suppose I offer you one of two lottery tickets with the same payoff:

Ticket 1: Provides a 1/10,000 probability of infinite bliss, or

Ticket 2: Provides a 1/3 probability of infinite bliss.

• The expected value of selecting each ticket is infinite (therefore, equal). Are you indifferent? No.
  • Lesson: When payoffs are equal, choose the most probable option.
• EAs already do this with catastrophic risks. They prioritize based on probabilities.
• Practical Upshot: Devote resources to religions in proportion to probabilities. Most resources to  most probably religion, second-most resources to second-most probable religion, etc.

The problem here is that if you advocate for the wrong religion, you might increase the chance people go to hell, because some religions think believing in another religion would make you go to hell. So actions on this basis have to grapple with the possibilities of infinite bliss and infinite suffering, and we often might have just as much reason to think we're increasing one or decreasing the other. And since there's no reliable method for coming to consensus on these kinds of religious questions, we should think a problem like "reduce the probability people will go to hell" — even if the risk level wasn't pascalian — is entirely intractable.

Pascal's Wager is an antique. If you want to consider long-term existential risk from the perspective of obtaining possibilities for infinite bliss, you'd better turn to old Fyodorov. Fyodorov proposed eternal bliss as an altruistic action—effective altruism—by our descendants toward their ancestors (us, for example) thanks to the development of futuristic technology. 

It's especially noteworthy because Fyodorov died before Einstein postulated that time is a dimension. Today, already very accustomed to science fiction (as in the movie "Interstellar" or the TV series "Devs"), we can consider that iseveral unknown dimensions exist, all of which raises the expectation that a future altruistic humanity will rescue all of humanity from the past and grant them "infinite bliss" (physicist Frank Tipler also proposes something similar).

Furthermore, this Fyodorov thing has the advantage of being adaptable to present altruistic action. By participating in an altruistic movement, such as EA or any other past or future, we could add the incentive that we are enabling a future high-tech altruistic civilization.

Taking this on as a cause area and talking about it can easily (and I would predict) backfire (IE increase probability of said event occurring).

If Alice is not thinking about whether to do X (say creating hell), then Bob actively trying to prevent Alice from doing X can increase the total risk of X. Bob will both bring X to consideration for Alice when it wasn't before, but also increase Alice's likelihood of endorsing X, due to ingroup-outgroup dynamics where beliefs are often flipped/inverted. 

In order to justify active opposition to X, you would need X to be not only possible, but a likely or default outcome. Something which has a very strong causal factor of occurrence, such that activism does not become the main causal factor. Such considerations should be taken more seriously before adopting tail-risks as an EA-cause-area.

Fun stuff!

The key question to assess is just: what credence should we give to Religious Catastrophe?

I think the right answer, as in Pascal's Mugging, is: vanishingly small. Do the arguments of the paper show that I'm wrong? I don't think so. There is no philosophical argument that favors believing in Hell. There are philosophical arguments for the existence of God. But from there, the argument relies purely on sociological evidence: many of the apes on our planet happen to accept a religious creed according to which there is Hell.

Here's a question to consider: is it conceivable that a bunch of apes might believe something that a rational being ought to give vanishingly low credence to?

I think it's very obvious that the answer to this question is yes. Ape beliefs aren't evidence of anything much beyond ape psychology.

So to really show that it's unreasonable to give a vanishingly low credence to Religious Catastrophe, it isn't enough to just point to some apes. One has to say more about the actual proposition in question to make it credible.

In what other context do philosophers think that philosophical arguments provide justified certainty (or near-certainty) that a widely believed philosophical thesis is false?

It probably depends who you ask, but fwiw, I think that many philosophical theses warrant extremely low credence. (And again, the mere fact of being "widely held" is not evidence of philosophical truth.)