@Cyracuz,
Quote: Some think it far more likely that there is nothing after death; that this is a much more rational belief than heaven or reincarnation etc. What is the justification for making assertions like that?
The bedrock of it all is the belief that the perceived world, and its additions from reflected thought and experiment, are the extent of reality which one needs to be concerned with (trapped in its rules or regularities, so to speak). It is assumed there are no "behind the scenes" affairs that are perpetually unknowable or that would make a significant difference even if they were. Accordingly, many traditional beliefs will be pruned away as not being the case, as more knowledge of the empirical world progresses (evolution, cosmology, etc).
Part of this assurance rests in confusing the "external world" (EW) with a "transcendent world". The external world is exhibited to varying extent by the sensory modes. In vision and tactile sensation, one's body is plainly depicted/felt as being engulfed by an outer environment. Great would be the folly of trying to deny the EW, so present as it is across the board in human perception (achieving its objective status via interpersonal verification and interaction with its contents).
But reason has a tendency to posit that this empirical world has a counterpart, a causal source or archetype for itself, that is not dependent upon the perceptual manifestations and the understandings of reflective thought and methodological procedures. And thereby is "invisible" to itself as it exists so independently of the preceding (apparently evidenced by the absence of everything before one's life/consciousness begins). This would make the external world a mere copy of a transcendent world, and invites the possibility of it being a very poor copy, that might deceive or conceal, or both, in the course of its inferiority. Especially after the everyday version of the EW itself has been called to task by science as being illusionary in many respects (i.e., even an unhidden world seems to have many masks it wants to dwell behind, albeit ones that can be stripped away).
The woeful circumstance above can be remedied, however, by discarding the notion of a transcendent circumstance (TC) even being a world, or an aloof archetype for this exhibited ectype. That wouldn't excuse the TC from being responsible for the external world, but only that is not bothering to represent itself in the latter, anymore than a brain is trying to represent itself in a dream. This would then make our EW, the empirical/phenomenal world, the natural world -- whatever the hell one wants to call it -- the only world there is or at least no copy of another, and featuring only deceptions and secrets that science can uncover.
And that is why I safely "treat" death as the end, regard humans as the result of evolution rather than creation, etc. Some older beliefs are not applicable to this world, which is where I'm located or exhibited.
However, it's part of a pretty large process (perhaps vaguely similar to a fractal algorithm generating ceaseless territory on computer monitors for viewers) which might include other universes with varying laws. And I have no idea what a transcendental circumstance is about, should there be such a power or complex of powers (I can hardly call it a "place", after the above!). Should I be "grabbed-up" in some peculiar sense after I die and a continuation or aspect of "me" posited somewhere else, where my arrival would not break any of that universe's laws -- then I will become concerned with the rules of that new game when I get there. Meanwhile, apart from the recreational amusement, there is little point in my trying to divine what an unknowable TC might or might not deal out to humans after death -- only concern about what this natural world is dealing out in the form of one peril or another.