So one of the more interesting parts of religion in the Inner Sea is that there are so many choices. Even for non-divine casters, depending on how your DM interprets things, gods are active forces in the world, and each has their own ethics, strictures they suggest/impose on their worshippers, and their own goals in the universe, which is much larger than just Golarion, particularly for gods with domains that interact with the Tapestry like Desna.
Yet deities are also socially isolated. Sarenrae is a "keleshite" goddess to many in the Inner Sea, despite having existed before humans arose on Golarion(I'm assuming, since the sealing of the Rough Beast sounds like a bad day Azlant would remember).
It's easier to explain for gods that rose more recently, like the Ascended Three, Irori, and Nethys, since their worship mostly spread from where they were once mortal, that same for gods like The Eternal Emperor, Nalinivati, etc.
Unlike omnipotent creator gods posited in our world, Deities in Pathfinder are limited. They can only pay attention to so many things at once, perhaps explaining why ancient gods don't have worshippers scattered evenly across the world, based on who's most suited to them. They build on existing cults and churches, and worship grows based on human noting their attention. Some may also have cultural biases of their own, or disadvantages. My favorite example of this is Mazludeh, who is mostly worshipped in Holomog, despite being an awesome NG goddess. But she's also very busy keeping the Celestial Concordance running, and is a giant snake person, which probably doesn't help with PR, given the classic 'snake' = 'bad' cliche being rather omnipresent within the setting.
But how do we expect this to evolve going forward? As Golarion advances (we know they do eventually figure out spaceflight and computers, despite magic tempting all their high Int people into the highly individual study of magic) their societies will crash together.
Even now, holy books of many religions are traveling all over the world, which means a lot of dogma is going to smash into each other. Does everybody abandon all the local deities and eventually gravitate to the major ones? Is there an advantage to minor gods? As power gamers we know some cleric domains are better than others, in-universe someone must notice that. And the gods themselves wax and wane: Asmodeus is one of the most successful Evil Deities because he can work with others and has spend eons establishing contracts and agreements and alliances. I get the sense if Lamashtu or Zon Kuthon get in trouble, they're going to have few people interested in helping them.
Starfinder isn't a great answer for this because of the Gap, it's a confounding variable that could have changed a lot of things in ways we don't understand yet.
So does anyone have any thoughts? Are we all going to be worshipping Iron Gods in a few centuries? Maybe a lot more mythic characters will rise and there will be an Age of Demigods? Or is the Luck Domain too strong? All Desna all the time?