I do doubt we'd get any actual religions but perhaps something similar to what the Sims Medieval did like introducing competing systems of belief. I do think the inclusions (the menorah object & attend holiday ceromony) we've gotten so far are well implemented features that allow us to hint at a sims religious background without delving too deep into a specific viewpoint.
I think a pack centered around general values/beliefs/spirituality for our sims would greatly benefit the game and perhaps be a way to reintroduce whims or as a more fleshed out way to do a wants/fears system that allows us to shape our sims personalities beyond their easily manipulated "emotions". This system would be a more long-term behavioral pattern of the sim that would shape how they behaved autonomously as well as how they reacted to certain situations forced on them by the player.
For example: we could have a romantic, family oriented sim that would rather wait for marriage to woohoo for the first time or have a ambitious, outgoing sim that get a significant boost when sharing their beliefs or encouraging others to join them. Perhaps a Lonor sim would be more interested in simply observing their spirtuality with themselves in a quiet room for hours on end. Maybe theirs a value for outdoors sims that simply makes them want to get out in nature more
In such a pack, the pool of beliefs/values would be pulled from several sources (both monotheistic and polytheistic). I think theres a way to do it tastefully in a way that would still make it interesting in game but not insulting to any belief.
