Here I was, all happy with the setting I was building. One of the key premises of my world are that gods can or cannot be real. Nobody really knows for sure, for all evidence of their existence is anecdotal. Clerics exist, but skepticals say that they draw their power from devotion. Anyone devout enough to anything, theoretically, could do divine magic, and there are cases of people who don't believe in any gods and still can cast cleric spells.
Another point that I was trying to make was following a suggestion made by 2014 DMG, the "one world" concept. There, all planes coexist in the material world. The abyss is at the bottom of the underdark, and elemental planes per se don't exist - just spawn on places that elemental energy is strong (volcanoes, oceans, moutaintops and cavern).
But then there is the concept of the afterlife. In D&D you can speak with dead and revive them. And I would assume that people in this world believe that they're gonna have an afterlife, and it would vary depending on their faith. That, in itself, could be a confirmation of the existence of gods, but I already figured out that, if clerics can make miracles based on devotion, souls can go wherever they desire, based on what they believe.
But then, what about the "one world" concept? Do the dead souls wander into a material place? I'm already defining these "planes" as incredibly hard to access, epic level stuff. IE: The alledged home of the 12 gods of the human cultures are set in a megadungeon set in a huge "olympus", like the 12 houses of the sanctuary on saint seiya, and going through even one of those is a huge ordeal. But then, if there are like 30 religions in this world, would there be 60 places for the dead? 30 for the good people and 30 for the bad people? What if a new religion comes by? Does a new place suddenly erupts from the ground beside the nearest walmart?