Who can create a Sect/Cult?
I suggest either a priest ,an elder or both.
Who can Schism?
I suggest an elder (priest) in the cult/Sect.
What do peasants do?
- If there is an temple they follow the temple
- no temple but an priest estate, they follow the priest(multiple priests mean half the peasants join new religion)
- no temple + no priest estate, follow the lords religion
- none of the above: half for each.
I'd say creating a sect should be an Elder, Schism would have to be Elder Priest. What the peasants do makes sense (with some randomness added because nothing in life is ever neat).