I considered Secularism as a name, but it felt too much like a government directed/imposed stance (i.e. more like a civic), rather than a change adopted by believers themselves. Secularism also felt broader in scope than just the Worship category. An apostate society has abandoned traditional worship, but they might still derive morality and such from their belief system.
This makes sense - I considered Apostasy as state atheism, anti-theism or secularization, therefore- a government imposed stance/civic. So it made no sense for it to be a tenet, set by great prophet etc.
How would apostasy combine with other tenets in other categories, like persecution? Can you, for example, still build inquisitors?
Also, currently, to see what tenets others have, you have to go to civics advisor.
It would be great to be able to see tenets of others in Religion advisor.
Then, it would be even greater if it somehow grouped civs with exactly same religion and tenets together, so that you can see at glance who shares your exact religion, and who shares religion but not denomination.
You could even assign names to the branches, based on tenets or civilizations (So e.g. Egyptians converting to Christianity would be called Coptic, Russians Orthodox etc. Then other Catholic civs who share their tenets would also be called the same).