Your logic is unsound. There is a huge difference between seeing that something is possible in principle and "a solid case", one that merits spending vast sums of money on. That difference is known in religious studies as "a leap of faith".
If you need that leap of faith spelled out, then these are the steps that must be true in order for cryonic preservation to be real and desirable (i.e. "worth it"): the scientific feat you describe needs to be really possible and not just in principle; humans are able to achieve this technology; the preservation process used today must be correct; technology must progress long enough for humans to achieve this technology; future society must be motivated to resurrect our dead; the kind of life offered in the future is one the preserved would desire; the resurrected would be able to adapt to future society; the resurrected would have the means to live a meaningful life in future society.
Sure, those are all valid concerns, but all of them are within the realm of possibility. We don't know if we'll achieve the technology, but we know we can in principle. We don't know if future people will care about reviving us, or that we'd even want to live in that future, but it is possible.
Note that there's no religion here anywhere, everything is casual and derived through logic from the current state of reality.
Cryopreservation is taking a fully <del>scientific</del><ins>materialistic</ins>, supernatural-free bet that gives you 0.1% (or 0.01%, or whatever) chance of not dying, when your only other choice is to die with 100% certainity. So unless you believe that you'll piss off God if you dump his promise and freeze yourself, you're better off cryopreserving than not. There is no leap of faith here, it's a result of plain utility calculations, if you agree that being being alive has nonzero utility while being dead has zero.
Those descriptors are not synonyms. There are many, many ways to be unscientific without any pretension of the supernatural. I think the word you wanted was to say "fully materialistic, supernatural-free bet".
The definition of science given by Francis Bacon and carried through to the modern era is that that a hypothesis is not accepted as valid until it has been tested experimentally, and a hypothesis must be tested after it has been formed (to avoid the sharpshooter fallacy). Modern versions allow you to use math, but that's as far as it goes. In this case, cryonics is obviously not scientific, because its effectiveness has not been demonstrated with the scientific method -- and that is what science is!
> ... chance of not dying, when your only other choice is to die with 100% certainty
You see, those aren't the only choices. I won't debate the chances of success, but assuming they are as high as you believe, there's a chance you're trading your certain death for an eternal life in a jar in some future hellish lab.
> Note that there's no religion here anywhere
There's religion here everywhere. I see people spending money for a chance at an afterlife they have absolutely no proof of. I see vast exaggeration of some anecdotal observations (miracles?) as "knowledge" of life. I see people finding comfort in an unknown future predicated on the powers of some super-human entity (at least super-human compared to the present) and on the optimistic belief in the benevolence of that entity. In short I see religious texts and religious arguments, hence: religion.
> I see people spending money for a chance at an afterlife they have absolutely no proof of.
There is a casual, down-to-Earth, no-supernatural-powers-required, fully constrained to known laws of physics and mechanisms of biology chain of reasoning that this could work. There's a huge qualitative difference between this and believing in God.
Sure, we can argue whether or not it's worth spending money on right now; if you start including things like "burden on your relatives" or "probability of undesirable future" or "probability that current preservation techniques destroy too much information" in your calculations you might end up deciding it's not worth the cost yet, but it doesn't change that the idea is sound in principle.
> I see vast exaggeration of some anecdotal observations (miracles?) as "knowledge" of life.
Are you calling modern molecular biology, chemistry and information theory a bunch of "anecdotal observations"? Sure, whatever. But even if, it's still the best thing we have to reason from.
> I see people finding comfort in an unknown future predicated on the powers of some super-human entity (at least super-human compared to the present) and on the optimistic belief in the benevolence of that entity.
You're bundling two different concepts together (which might be excusable, because people who believe in cryonics also often believe in superhuman AIs). Still, cryonics does not depend on any super-human entity or its values, it only depends on whether or not we crack nanotech (or some other technology we don't know yet).
> In short I see religious texts and religious arguments, hence: religion.
Where you see religion, I see reasonable assumptions based on current scientific knowledge, extrapolated by applying cold, hard rationality.
> There's a huge qualitative difference between this and believing in God.
Don't confuse God with religion. A lack of deities does not make this not a religion (see nontheistic religions[1]). Also, why are you discounting what you call "supernatural" beliefs? Even physics is based on some assumptions (laws of symmetry) and ends at the big bang. If you look at the past 50 years of medicine and biology -- especially human biology -- you'll find many wrong conclusions (see Ioannidis's "why most published medical research is false"). You're exaggerating our scientific capabilities while discounting the limits to our understanding. In fact, you're turning science and technology into your religion. Don't overestimate human capacity and don't underestimate our stupidity (but don't do the opposite either).
BTW, I'm not even sure cryonics falls under the category of nontheistic religions, as "humans" with the power to resurrect the dead (and by extension eliminate natural death) are no different from a deity. Your religion is justified by what we know, as were others. The only qualitative mistake here, I think, is yours: as people who know (some) and love science, we know that it has limits. We have limits to observation, and, most pertinently, we have limits of tractability and understanding of complex systems. I don't think scientists assume we'll one day know something, and they certainly don't assume we'll have a specific far-fetched technology.
> Still, cryonics does not depend on any super-human entity or its values
I wasn't talking about AI, I was talking about future "humans" (is that what they would be in a world without death?) with technology we do not possess, hence super-compared-to-us-humans.
It's not a lot of money actually, it's just life insurance, a portion of which is allocated to Alcor in case cyropreservation is possible after death. Maybe $20 a month or something depending on your age when you got the policy, plus an annual fee that is mostly deductible as a charitable donation. I consider this fee donating to science, since Alcor actually does good science and publishes research papers. So $20 and a dream and maybe you get to try again.
It's not a risk free investment by any means, but it doesn't require heaps of denial involving topics of science like evolution, intolerance of others, or any dogma. If you want to think cryopreservation is like a religion by all means do, but you're not convincing me.
I don't think cryopreservation is like a religion; I've proven that's the case (albeit a religion without a personal deity, but there are others like that, I think). You're simply claiming that cryonics is a true religion, which might well be the case. In any event, I don't see spending money on alleviating the fear of death as wasteful by any means. That's how we spend most of our money anyway.
If you need that leap of faith spelled out, then these are the steps that must be true in order for cryonic preservation to be real and desirable (i.e. "worth it"): the scientific feat you describe needs to be really possible and not just in principle; humans are able to achieve this technology; the preservation process used today must be correct; technology must progress long enough for humans to achieve this technology; future society must be motivated to resurrect our dead; the kind of life offered in the future is one the preserved would desire; the resurrected would be able to adapt to future society; the resurrected would have the means to live a meaningful life in future society.