Actually, I think we are going round in circles, so perhaps we should call it a day.
Perhaps you are right. I've been mainly responding to questions and claims, leaving it up to you to put the pieces together. So maybe that's why I haven't been able to relay the sheer weight of evidence and logic involved. Perhaps if I were to start you on your own journey of discovery with one small example and a clear-cut definition.
Afterlife: A continuity of personhood following the death of the brain-body system.
If you have some other way of defining afterlives, then we'd have to look at that separately. That might include some versions of reincarnation where people are reborn as animals ( or whatever ). That's not what I'm talking about. I'm talking about the assumption that we lose nothing that counts as part of who we are following the death of the brain-body system.
Right away we can see that if we are to go with the above assumption, we lose a lot right away — our entire brain-body system is gone. That is the primary means by which we typically establish our identity. Without it, what's left? We might claim that so long as we have our personality, then that's sufficient. I don't think it is, but for the sake of argument let's assume that our personalities survive the death of the brain-body system.
Looking at the issue of personality, there are mountains of evidence that the brain-body system plays a crucial role in personality. For example various types of injuries and drugs radically affect our personality. But even assuming we don't interfere with anything, our perfectly healthy natural state still requires a plethora of biochemical agents in order to maintain our normal personality.
Just the hormonal differences between men and women make huge differences in personality and identity. So ask yourself. That being the case, what takes over for all that once the brain-body system is gone? There are reports of apparitions that look identical to the deceased, therefore something else has taken on the task of replicating a body image.
Then what takes over for the hormones and other biochemistry that regulates our normal personality? Obvious
something must. What takes over for our visual receptors ( our eyes ). Optics shows that our visual perceptions come directly through them — not from some remote source. What takes over for them? Start adding it all up, and what you end-up with in order to retain any semblance of identity and personality is a copy.
The original you, along with everything that allowed anyone to identify you as being
you, is now either six feet under, or a pile of ash. So whatever this copy is, it's not the original you, even if it thinks it is — unless of course as has been said already, this realm is some sort of Matrix like construct ( the brain in a vat problem — elementary philosophy ). Those are the only two options.
Now given those two options, either way, we still are thinking individual entities, which means that we have some version of a brain
someplace. But consider how much more we have to assume with that model than just assuming that we are in a universe governed by nature, and that we are self-contained autonomous, intelligent, beings that evolved here and are trying to figure it all out. The latter seems to be the simplest model.
Then again, just because it's the simplest answer doesn't mean it's the right answer. From here things start to get more complex, involving mutiverses of various kinds and whether or not time is quantized. But if we can get this far along in the journey, then we are at least recognizing the only two options available, and that either way, they're not really the same sort of "afterlife" that people typically imagine.