The term “mystery cult” is used to refer to certain religious organizations which flourished in Ancient Greece and Rome. Membership in these organizations was closed, with proceedings only open to chosen initiates, and these groups were extremely secretive by nature. Historians have a variety of sources for information to draw upon when researching the mystery cults, including the writings of people who participated in rites and ceremonies associated with these organizations.
Both Greece and Rome had state religions, with all members of society participating in the worship of the gods. Greeks and Romans visited temples, held sacrifices, and prayed to the gods both publicly and at home, and most had altars at home for personal worship. For many citizens, the state religion was enough, satisfying the need for religious faith and practice.
For others, however, the state religion felt insufficient or incomplete, and as a result, mystery cults arose. Members of these organizations worshiped specific gods and goddesses, often picking obscure individuals to focus on, rather than well known and already well-worshiped individuals. Some mystery cults even integrated religious figures from other cultures; Isis, for example, was worshiped in Rome. Some famous examples of mystery cults include the Eleusinian, Dionysian, and Orphic Mysteries, although numerous other groups existed as well.
The “mystery” in “mystery cult” comes from the Greek musterion, which is used to refer to a secret doctrine or rite. When people joined the mysteries, they were forced to go through an initiation, and they were expected to guard the secrets of the organization. People who disclosed secrets from the mysteries could be subjected to severe punishments or public castigation, as the defining feature of a mystery cult was its exclusivity, so revelations about the doings of a mystery cult would been quite undesirable.
The goings-on at ceremonies and parties held by some of these Greco-Roman cults are rather infamous. In addition to holding animal sacrifices, some mystery cults also had lavish meals, threw elaborate parties, and engaged in a range of activities which would have been considered unsavory, even by people of the time. Initiates of these mystery cults took drugs to enhance their religious experience, and evidence strongly suggests that members engaged in a variety of sexual activities, as well. The combined allure of secrecy and socially unacceptable activities must have been a strong draw for many mystery cult members.