....I am making a life after death belief system? Who is with me?
Go for it. I suggest that you don't try to push it on anyone. That tends to put you in bad situations. Instead, just make references to it now and then, and don't worry about all the characters in game picking it up. They tend to find out regardless and choose on their own.
If this is a new character, I would also suggest that you make him a tribal who has come to the big city. A tribal is much more likely to have a belief in such a thing.
Kudos.