There are multiple major religions in the world of Darkening Stars.
Alephenity is a religion centered around the teachings of Ale. (pronounced as two syllables) It is the widest spread religion in Entherstia, and is mostly followed by humans.
Novemism is a religion practiced primarily by felines. There are nine scrolls of scripture, often bound as a single book.
As an overview, practitioners of Novemism believe that a soul has nine lives completely independent of each other. There is no way for a soul to know which life it is on, or what its other lives have entailed.
Imperial Novemism teaches that there is only one god, and that he holds a balance. If a soul has lived its lives in service to demons, they are sentenced to an afterlife as a servant to them. However, if they have lived good lives, they will ascend after their final life and become an angel.
Astral Novemism teaches that there are nine gods and nine demons. Each god/demon couple command a different kingdom of the world, and each life is lived as a test between one pair, each tempting souls with opportunities either good or evil. There are 512 (29) different afterlives that a soul can be sorted into, based on which gods/demons they have catered to over their nine lives.