Mysteries, in religion, are secret ceremonies. They may be witnessed or participated in only by people who belong to, or are about to join, the group that practices them. A person joins a group that practices mysteries by undergoing a process of initiation. This process ordinarily includes indoctrination, moral testing, and a rite of purification. Those who are initiated promise never to reveal the group’s secret ceremonies and doctrines. Mysteries have been part of many religions. The secrets of early mysteries were so well kept that our knowledge of them is incomplete.
Mysteries were important in ancient Greece and in ancient Rome, beginning in the 600’s B.C. One of the most famous Greek mysteries was practiced by a cult in the city of Eleusis near Athens. In early autumn, members of the cult performed what were known as the Eleusinian Mysteries. These mysteries were based on the worship of Demeter–the goddess of fertility. Initiation into the cult included a symbolic cleansing in seawater. Those who joined the cult were promised happiness in an afterlife.
In ancient Rome, mysteries were practiced by members of a cult called Mithraism. Mithraism, which was practiced only by men, became popular among Roman soldiers. Cult members worshiped Mithra, the god of light who was originally worshiped by inhabitants of Persia. Initiation into Mithraism included a symbolic washing in the blood of a sacrificial animal.
Other mysteries practiced in ancient times were connected with the worship of the god Dionysus in Greece or the goddesses Cybele and Isis in Rome. Mysteries also became part of religious worship in early Christianity. Christians received the Eucharist in secret rituals. However, after Christianity became the official religion of the Roman Empire in the early 300’s, the sacraments became more public.