There's endless ritual shit you can do, with cool props and magic spells and stuff. Theres two thousand years of the nerdiest, most intensely naval gazing fan-fic to read through. There's thousands and thousands of saints you can have a parasocial relationship with. There's a bunch of weird social clubs and professional orgs and secret societies to join.

It's big and it's got a lot of inertia. The cathedrals are very pretty. Even shitty catholic churches probably have some cool stained glass windows or alter pieces. It's much more formal than a lot of protestant churchs. You don't have to make anything up because it's all written down in excruciating detail. The rituals and the theology and the practices are the same in most catholic churches in the world. It's stable, youdon't get the constant schisms and fragmentation some protestant denominations go through.