It was a while ago. Here's a referesher
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To that old nugget, I might add
Ma'at is a legal principle, so you didn't have to believe in or worship Osiris/Anubis/Re/Horus/Amun/Whatever to be judged positively by that feather (and
attempts to enforce an orthodoxy were not always met well), that
staight vegetarians who happen to not be Jewish but who might be, say, Christian, Islamic, or even certain flavors of Hindu are gonna be pretty OK in Jewish eschatology (such as it is), that
certain flavors of Greco-Roman paradise cared if you were "good" but didn't give a frig about if you thought Jupiter was a great guy or not, that
there's about as many Christians and Jews in Janna as there are Muslims according to the Hadith, and probably MANY MORE pre-Islamic people, and that
the current pope expects to see athiests in heaven with him.
Those all, to varying degrees, are DEFINITELY toleration of faithlessness. In fact, it's more typical to have a place for "virtuous pagans" than to exclude them. All unbelievers being punished for eternity is not a concept that has been common throughout history. Why would the Realms be different?
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In FR specifically, the gods are little more than magical people - no different than powerful archwizards or mighty dragons. You've got
elves that are older than some of the gods floating around the setting, and Elminster has survived the death of DOZENS of them. Sometimes, they're
literally magical people - human beings who underwent apotheosis. In a world such as that, there's no more reason to worship Azuth "because he's a god" than there is to worship your local beholder "because he's a frickin' beholder" (there might be MORE reason to worship the latter, if he's nearby!). All being a god in FR means is that you control some aspect of the world as a whole. That means you need to be dealt with, but it doesn't mean you deserve to be honored and respected and worshiped. Giving lip service to the gods or not really giving a frig about 'em or even going all "Rage at the Heavens" are all reasonable responses to these powerful entities, just as they are reasonable responses to, I dunno, Lord Neverember. What's so bad about not worshiping the gods that makes it different from not worshiping a pantheon made up of the Lord's Alliance? The Dragonborn are even canonically "What's so great about gods?" kinds of people. There's no real satisfying answer to the question they pose, unfortunately.
Here is the problem with your post, none of this implies faithlessness, as in you don't believe in the gods (except the new pope of course who is completely outside of the Catholic Doctrine). This is an acknowledgement that the gods will not choose based on what you believe in, but rather how well you adhered to the rules of their society. For example, even a devout believer in Ra is not guaranteed paradise in the Egyptian afterlife. They are all judged according to the feather because that is the method according to the priests. It wasn't even considered that you were faithless in their religion.
Egyptian Pantheism did not require the individual worship of a deity. It was assumed that the gods existed and all knew this as fact. Individual worship was not required because the entire pantheon was worshiped as a whole. You prayed to the appropriate god. But once again, this is not faithlessness.
I've spent time talking with Muslims on this issue. Christians, Jews, and Muslims are considered people of The Book. All are accounted believers, not faithless.
Not thinking Jupiter is a great guy is completely different from being faithless. The Greeks were a surprisingly religious and superstitious people. They worshiped a pantheon, not individual gods. Each god did not have their own individual afterlife area. Once again not faithlessness. All Greeks would be judged and sorted when they were dead.
The Jewish folk don't even necessarily believe in an afterlife.
https://www.jewishvirtuallibrary.org/jsource/Judaism/afterlife.html So bringing them up is kind of a moot point.
Faithlessness is something completely different than anything you cited as an example. Faithlessness is a lack of belief in the gods. I notice you seem to think that never praying or paying proper homage would be adjudged good behavior in the religions you cited. That is false and far from the truth. There are still rules to follow created by the gods to assure your passage into paradise in all your examples. That means the gods decide what is good and what is evil. They judge you accordingly.
Now perhaps you have a problem with the way the FR worded their afterlife punishment for the faithless because a person that dies without having chosen a patron deity isn't necessarily faithless. Faithless may have been a bad choice of words, though it does fit the concept of what they were going for with the
Wall of the Faithless.
Given the FR isn't set up as a pantheon of deities servicing one group of people or a monotheistic god that all people must answer to, both having a single idea of an afterlife, as all the examples you cited, I think the solution in the FR is sufficient for their version of polytheism. The rules are clear. The punishment for breaking those rules are clear. How exactly does that differ from the other religious examples you cited? They still punish people for violating their rules, even if those violations aren't necessarily "evil" by modern standards. How would we choose between evil and good when there are so many different deities that might have different ideas of virtuous behavior? If you want something different, what exactly would you recommend in a world with no single managed afterlife or single paradise for the good? Who would make the decision of who was good and who was evil? Kelemvor? Where would he send the good? Who would protect them in the afterlife from the predations of the evil? A god being the faithless person swore no allegiance to?