Treasure Island Spirutualism

The natives of The Treasure Islands (Falias, Finias, Gorias, Murias) believed that the four islands (sometimes five, including Brittia) were all there was of the world, and were surrounded by a sea that eventually flowed into oblivion
The natives would often believe that everything, including inanimate objects, had some sort of soul and subjective experience, and they would all communicate with each other in some way.

Mythology & Lore

Before the world was created, the quadruplet deities Fali, Fini, Gori, and Muri decided to work together to create a large island known as Aeon. Fali created plants to consume the soil, Fini created animals to consume the plants, Gori created humans to consume the animals, and Muri created thoughts to consume the humans.
Eventually, the four siblings began to have arguments about what to do with their new creation. Eventually, they settled on splitting Aeon apart into four individual islands, with each god allowed to do what they please with each
Under some beliefs, Filí, a half-sibling of the quadruplets, wanted their own part of Aeon. They laid claim to part of Muri's island, and created entropy to consume the thoughts. When the quadruplets began fighting, Filí used their power of future sight to predict that Aeon would soon be split apart, and in the process would destroy their part of land. Preemtpively, they broke their land off from Aeon and formed its own island. This island was often named Filías, but no known natives inhabited this land, and it was renamed to Brittias when Camelot took over.

Sects

Mathamism - a sect of Absolutionism formed during the Camelot colonization of the islands that combines the principles of Absolutionism and Treasure Island Spiritualism
Treasure Island Purism - After its introduction to Avalon and The Boundless Expanse, a lot of the Treasure Island mythology fell apart. Treasure Island Purism refuses to fall apart, and outright rejects the existence of anything outside the four islands