Here's the religion that reveres nature and the volcano. I've left it fairly open to interpretation so there can be a variety of denominations and the like.

Ilinucism is an ancient faith that worships the earth itself as a living deity. The world-mother, also known as Aketa, is the mother of all things in the world, living and nonliving. Ilinucism has many denominations which all of which hold the same core beliefs. Perhaps the most important of these beliefs is that when any living thing is born, Aketa blesses it with a portion of her soul, thus blessing it with the gift of life. When a living being dies its soul becomes one with Aketa. The volcano is a holy place, Aketa’s mouthpiece by which she speaks to her children. It is a place to be shared with all of the faithful. Those capable of using magic are seen as saints who have been blessed with an abnormally large amount of Aketa’s soul. They are superior people who should lead their brothers and sisters in their mothers’, Aketa’s, name.