Your challenge if you choose to accept it is for a major and mainstream religious group to worship a being that is considered to be traditionally evil (Think a religion worshiping Angra Mainyu, or one worshiping Ahriman, or one worshiping Loki or Fenris, or a group that worships Satan.)
This group needs not to be morally evil and they can/most likely will add things that modern people would consider morally correct into their religion. For example a form of Gnostism that worships Satan as the true god and a rebel against the evil Demiurge would count as fulfilling this challenge.
Bonus points if the religion can coexist peacefully alongside their opposite religion. For example the Gnostic Satanist coexisting alongside a group of Christians.
This group needs not to be morally evil and they can/most likely will add things that modern people would consider morally correct into their religion. For example a form of Gnostism that worships Satan as the true god and a rebel against the evil Demiurge would count as fulfilling this challenge.
Bonus points if the religion can coexist peacefully alongside their opposite religion. For example the Gnostic Satanist coexisting alongside a group of Christians.