Yeah to be honest this whole statement was probably completely unecessary and probably just did many of the things you were saying we should avoid doing...
All the religions are completely fictional, with fictional theology, history, and deity, you will be able to find some similarities with real life, because, well, real life and history is a great source of inspiration, but beyond the broad concepts of monotheism, polytheism, reformational splits (within a theological group) Centralised and decentralised hierarchy, etc. This is all just made up.
The idea of religion and ideology is so central to systems of power and human identity, that really a 'Medieval Kingdom Simulator' needs to have Religion as one of the 'Balancing Elements' that a King or Queen must consider and/or use to maintain there upward trajectory to ultimate power and dominance!
We will have somewhere in the region of 13 religions to balance and differentiate.
Which has already begun, what we don't yet have is the basic framework of what religion will do and effect broadly across the game.