It's a big part of their belief system. From the start kind of thing. Also not willing to change it at all for personal reasons. Not the only thing that doesn't change in any case, Reon and Mayon always get the same symbols and same kinds of prayers applied to them. Lilies get sacrificed to Reon with fire and roses to Mayon with water and all.

Variety is more in that say Ithillin believes much more in an earth deity.

Technically all the same pantheon though, but divided up with people actually worshipping different parts of it. Then you have stuff like the Nem goddess and all.