There is a growing recognition in sociology and anthropology that whatever beliefs in how to lead a good life are left after you remove facts and knowledge about the world, are equivalent to religious doctrine, even if non-deist. Most people, including highly educated liberals, have such strong beliefs.
I'm guessing you didn't explain "after you remove facts and knowledge about the world" very well because removing facts would indeed leave you with beliefs in non-factual stuff by definition.
That is not too far from believing in the afterlife, if you come to think of it.
It’s extremely far. One has a chain of reasoning and supporting data. The other does not.
They’re both assumptions, since everything about the future is an assumption. But some assumptions are “better” than others, for lack of a better word.
On the other hand, believing that your actions have consequences, and that you will pay for your mistakes, is a very good assumption. But in the sense that you mention, it's "unsupported". This lack of evidence may lead me to conclude that societies are hung by a thread, and that collapse is imminent. It could be, but societal collapse simply hasn't happen after an unexpected, global, unprecedented turmoil.
Why some assumptions are "better" than others? THAT is a very good question. My take is that there aren't a priori: some societies believe some assumptions, and survive, and others don't. In a sense, to me, assumptions are only good in retrospect, and it's an idea that "feels" correct rather than something I can "prove".
Touching something too hot transfers excessive energy to your skin and registers as pain.
Walking without looking at where you’re going can cause you to not notice uneven surface and affect your balance causing you to fall.
Attending a higher education facility and obtaining credentialing and skills in a field with high demand in order to be able to trade it for money so that you can then use that money to pay for shelter and food and medicine.
The above are all assumptions until they actually occur, but they are different than assuming an afterlife simply because you feel like it (for example, it satisfies one’s ego to assume a piece of them is immortal. Not that there’s anything wrong with that, do whatever makes you feel good).
Ironically, basically all physicists of the last ~100 years went through university in order to study physics. What do you think was their "rationalization"?
I suspect most people who believe in an afterlife have a chain of reasoning and supporting data to back up their belief, too. Personally, I don’t believe that reasoning is sound or the supporting data is high-quality or convincing but I also don’t think the distinction you’ve drawn is really all that meaningful.
I propose an alternative: any arrant nonsense that people insist on believing despite facts and knowledge is likely to be willful ignorance, which people may seek to protect by calling it religion.
The arrant nonsense no one believes anymore is called "mythology".
For example, where I live, nearly all people wear clothes, and they generally think that wearing clothes is important - even if the weather is mild enough that you won't get cold or sunburn if you dispensed with them. Moreover, they will get upset if other people dispense with theirs.
What I find funny is that people will ridicule organised religions for prescribing certain clothing (such as Mormonism, Sikhism, Islam), blissfully unaware of their own quasi-religious attitudes towards clothing.
And sometimes these attitudes can be quite extreme. There is a man in the UK who has been in prison for years for indecent exposure. Every time he is released from prison, he strips off outside, and they call the police to re-arrest him.
I agree that this is true about human communities.
However, what each community chooses to affirm is important. Do they believe themselves to be the Master Race? Do they believe narcissistic creation fantasies? Do they assert an understanding of electricity, physics, evolution?
Only some of the above "principles" are true, regardless of what the community prioritises.