Mystery cults, or mystery religions, were ancient religious associations characterized by secrecy and initiation rites. They typically surrounded one primary deity, but some mystery cults venerated multiple deities in their rites. Members of mystery cults were required to maintain the secrecy of the cult's rituals and knowledge, which added to the cult's prestige.
This is a companion discussion topic for the original content at https://www.worldhistory.org/Mystery_Cults/.