I'm a lot more OK with the Wall of the Faithless after reading the discussion here than I was before. Only knew a tiny bit.
Unfortunately a lot of the discussion re: the Wall of the Faithless here is misleading, which is unsurprising given the FR's messy canon.
People are going on long explanations/apologia and not even getting the god who created it right!
The reality is, it's a grim and even vile concept that really undermines the entire idea of faith in any god in the Realms, by making it essentially coercive in nature, which seems, oddly, to be what Ed Greenwood intends. His own most recent major FR book certainly seems to portray FR worship as somewhat coercive in nature, and he doesn't seem to think anything is wrong with that.
Whether Kelemvor has "stopped it" depends on exactly what you read and when, but canon is that that's not true. Greenwood himself doesn't seem to acknowledge the Kelemvor exists, at least recently. SCAG is more recent than any other official works which involve the Wall, and features Kelemvor maintaining as a punishment for failing to worship a god, being the same utter horror/atrocity that it is in earlier works.
So if you're okay with it because you think an evil god created it (they did) and Kelemvor just couldn't break it, but replaced it, that's not actually current canon. Current canon, or as close as we can get is that it's working now as it always did, destroying the souls of anyone who:
A) Didn't actively worship a specific god.
or
B) Did actively worship a specific god, but that god got killed before the person died.
(Bureaucracy!)
or
C) Did actively worship a specific god but is rejected by that god for any reason.
(And we all know exactly how petty and mean-spirited even many of the G-aligned gods in the FR are)
So it's really just purely grim in canon.
@wingsandsword Most of what you're saying is not up-to-date. You seem to have decided to reject the most recent canon in favour of an older canon which you like better.
That's fine for your game, but it's misleading to state the stuff
as fact that you're stating. In fact you're putting quite a lot of spin on a collection of your favourite bits of "older canon". Also, the entire idea of "faith" and "true believers" is pretty silly when the gods walk Toril. It's a bit like having "faith" or being a true believer in Superman (were Superman real). That's a circle the FR has never been able to successfully square, because contrary to what you're saying about modern views on faith being incompatible with the FR and so on, it's clear that FR writers have consistently striven to somehow jam together a sort of Greco-Roman take on the gods with a modern Western-style view of "faith" and it's value and so on. And the result has been a terrible mess.
Here's an example of something you're claiming as fact, which I don't think is supported by a single modern canon source:
If you never followed one in particular and weren't particularly devout, then you end up being claimed by one who fits your general personality and alignment. A random farmer will likely be claimed by Chanuntea. A random soldier might be claimed by Tempus. A lawful good individual might be claimed by Tyr, and a neutral good individual might be claimed by Lathander.
That is a gigantic "CITATION NEEDED" right there. I cannot find any FR source, on a quick flick through of the ones on my shelf (and a couple of PDFs), which supports this take - specifically that gods swoop in to "rescue" the souls of people who didn't actually worship the gods.
Further, the idea that you have to "deny" the gods is directly contradicted by some fairly recent sources. Greenwood's book on the customs of the Realms and the like (I forget the name) is pretty clear that anyone who doesn't ACTIVELY worship the gods, by prayer and by offerings, is going to be in a whole lot of trouble.
I can probably do some cites later if you need them, but you need to cite the above first.
@M.L. Martin That take on the Cataclysm does make vastly more sense. Do we have any idea why it was abandoned in favour of the far less convincing take they went with?