It's by design. Religious leader isn't necessarily the same person as the founder

Hello Resand, 

Might I ask where I can read up on some of the intricacies of the Religion mechancis??

Thank you, 

~Ran

The Humankind Wiki has some great articles that have helped me understand the game. 

https://humankind.fandom.com/wiki/Religion

I'm having a similar issue... How do I convert my state religion to something else? As soon as I established my own religion my followers got gobbled up so I've had diplomatic penalties with neighbors the entire game as I'm unable to change my state religion :(

Thank you Gelberhund.

GB, if you read that link it will explain how most of that works.
As for changing religions, I haven't quite grasped that yet, but I had an event to switch to Atheism.

Gotta push heavily into Faith, or ignore it apparently.

~Ran