Why not this:
Remember the old liege/vassal point system?
Incorporate it into a religion like this:
A priest cannot be kicked from a religion unless they have so many black marks (based on the number of elders). Makes it so an elder can now be involved in supporting a heretic or undesirable, and makes church politics more politickier. At the same time, it makes it so if there is a general consensus among the elders that a priest should be removed, they can be.
In summary, elders get the ability to give good/bad marks to priests, and a priest who accrues enough bad marks can be kicked.
I don't like this on the basis that it can be gamed. If the top elder wants it done, all he has to do is demote all of the other elders temporarily and all of a sudden he'd have all of the freedom he desires? I don't think restrictions are worth it if they can be gamed like this. I also don't think the marks system ever really worked all too good.
