From The Art and Popular Culture Encyclopedia
Pre-Christian religious mysteries
The mystery religions of antiquity were religious cults which required initiation before a participant was accepted. They included Eleusinian Mysteries, Mithraism, the Cult of Isis, and the Cult of Sol Invictus.
- Greco-Roman mysteries, a class of religious societies of the Graeco-Roman world
- Western mystery traditions, a broad spectrum of spiritual traditions found in Western society.
The term is used in Eastern Christianity to refer to what the Western Church currently calls Sacraments and Sacramentals. In the Early Church they were kept hidden from the pagans — the so-called Disciplina arcani — lest they become objects of ridicule. As the Age of Persecution ended, the secrecy was gradually relaxed. But the term continued to be used. Originally the term "Mystery" was used in both the East and the West, as shown from the "Mystagogical Homilies" of St. Cyril of Jerusalem and the work, "On the Mysteries" by St. Ambrose of Milan.