The downtime, building, and organization rules in Ultimate Campaign could also be useful in quantifying how much reach and influence a church leader has, if you want that level of detail. The character's actual rank will still need to be judged by the GM.
There is at least one AP where PCs have the option during the downtime between books to work with the local temple and gain a place in its hierarchy. My oracle PC did that, as well as taking Leadership a book or two later. My group has only completed 4 of the 6 books, so I don't know yet how much that status will play a part in the rest of the AP (if any), but my PC would certainly be interested in taking a bigger role in the priesthood after the current in-game crisis is resolved.