I like Devs idea for religion to be a mechanic on its own, not just a “faith meter”.
However creating a new mechanic out of the blue is not an easy task from GD point of view.
What if religion doesn’t have it’s own mechanic, but works as a set of custom rules for your people? (Inspiration points: Crusader Kings or Rimworld).
Religion consists of sets of rules on pretty much everything.
For example one religion has Sacred Land rule forbidding or penalizing you for building any farms, but giving +200% to natural resources collection or warrior culture when every colonist wants to wear a weapon or gets mood debuff and so on.
Is it gonna be “balanced”? Hell no! Is it going to be re-playable and fun? For sure!
Also, as long as it works as custom rule set it can be safely ignored by new players.