I liked it because the sims religions had their own system of ideas at the base of them. I would love to have at least one fictional sim spirituality in the game, but without much as far as beliefs defined. This would allow the players to fill in all the blanks about what sims believe and how they participate in their faith.
I love making up my own sims customs and traditions, as well as my own sims "conspiracy theories" that some sims are able to talk about with one another. So if there was a trait such as "spiritual" this could enable sims to talk about spiritual things. As far as gameplay goes, this could easily be used to make up all sorts of various spiritual beliefs that sims could have that do not in any way resemble real life belief systems.
When sims discuss conspiracy theories, you don't get a pop-up saying they're talking about something real-world based. You don't get any indication what they're talking about other than some sims believe in conspiracy theories and react positively to these topics, while other sims don't like it or are bored by it. The same could be done with talking about sipiritual beliefs.
