I had an idea for how religion could be implemented in the future of this game (not necessairly at release so then the Devs can test the system to make sure its not broken)
The idea is that a civilization could research the technology needed for religion and then have the opportunity to found one.

Players that earn access to religion can create a pantheon of gods. (3 gods from a list of existing gods in other cultures like Egyptian and Greek). Each god gives a benefit AND a downside and players are unable to pick 2 gods that could offset the downsides.

E.x. The player picks Osiris as the ir personal'Figurehead' god. He gives a boost towards production of cultural buildings since he was the god of the Undead pharaohs, however the need to focus on producing cultural buildings adds an increase of X amount needed to build other types of buildings as well. So while it may take 4 turns to build a theater, it could take 7 or more turns to build an irrigation system. 

The three categories of gods reflect different parts/concepts of the game. One would influence city production and buildings, one would impact military combat (E.x. having an increase of bonus attack with chariots at the cost of losing defense for naval units), and one would be a 'wildcard' in that a player can choose one more god from one of the previous 2 groups AS LONG AS it does not offest/impact the originally 2 chosen gods. This would prevent players from breaking the game with having an overpowered army or navy. 

As for other civilizations, they could have a choice as well. Unlike CIV VI, players would have a choice in if they want to found a new religion or follow an existing one. Let's say player 1 founds a religion and later on, Player 2 earns the same technology needed and has discovered player 1 already. Player 2 could chose to follow the religion that Player 1 is following in its entirity, or they could found a new religion of their own. Now here's the interesting part to make it more 'realistic'. Players that found a new religion after the first one can use at least one god or goddess from a religion that already exists before needing to chose the other 2 from the list that have not been claimed. So lets say Player 1 has Osiris, Set, and Ra because they are playing as Egypt and Player 2 wants that cultural building boost that player 1 has. They would be able to pick Osiris and then they could chose 2 new gods, like Artemis and Apollo, so that they can still benefit from at least one part of Player 1's religion. Then of course they can just choose 3 new gods entirely if the player does not like any of the choices made with a religion's pantheon. This would reduce the 'OP'ness of religion in the game of players feeling that they would always need to rush research into founding a religion. 

Other Concept

Holy Relics: Can be found as a very rare find from exploring the map after founding a religion. They can be used in association with any of the gods to create an increase in a god's benefit that applies to ALL religions that have the god in their pantheon. E.x. Someone finds a holy shroud that they associate with Osiris, so every player that has Osiris in their pantheon gains a better boost in cultural production or maybe the downside of having picked Osiris is decreased.

What are your peeps' thoughts? Do you think Humankind could implement a religion system in the game like in CIV VI? If they already plan to implement religion then I apologize for the long post then. 

Either religion is something to play with or a passive system that grows by itself and throws events at the player. What should it be?

About religion(s), last Tuesday, the Creative Director of Humankind (his online nickname is Spacetroll_Amplitude) answered a bunch of questions on Reddit. Specifically about religions, he wrote :

I guess we'll have more explanations about it in the next coming weeks, maybe even a Feature Focus video specifically about religions.

But so far, either on the press tour gameplays walkthroughs or the current OpenDev scenarios, Religion mechanics are not implemented.

Small hints appear here and there though, either in Civics/Technologies  trees or on certain buildings (some giving faith bonus for instance).

Dormantus wrote:

I really hope they will come with something quite different from Civ6. There are things to like about that implementation, but gameplay wise its too easy to ignore it, while not miss anything. Its too separated from rest of the game, and on top of that, unless you invest to it massive amount of resources, its benefits are negligible.

Also I really dont like the concept of creating and controlling religion, feels very artificial and burdens you with more micro. I would rather see some organically rising cults and religious traditions, semi-independent from culture of origin, which you can influence or exploit in some ways.

I second this. I hated how Civ 6 implilmented religion. I would rather it be more event based and semi-independent, like you said. And I hope there is a way to adopt a society without a state relgion in later eras because thats how things evolved in the real world.

It was interesting that some of the event choices in Scenario 1 contained some faith options (Solar/lunar calendar, Pecking of Poultry, & Keepers of the Creed). I hope religious tenets developed based upon previous event choices instead of selecting the most benefical ones from list after accruing enough points (Civ 6).

It feels like avenues to faith are woven into events which I hope will be just as benefical as economic and miltitary choices.