Mystery religions, sacred mysteries or simply mysteries, were religious schools of the Greco-Roman world for which participation was reserved to initiates (mystai). The main characterization of this religion is the secrecy associated with the particulars of the initiation and the ritual practice, which may not be revealed to outsiders. The most famous mysteries of Greco-Roman antiquity were the Eleusinian Mysteries, which were of considerable antiquity and predated the Greek Dark Ages. The mystery schools flourished in Late Antiquity; Julian the Apostate in the mid 4th century is known to have been initiated into three distinct mystery schools—most notably the mithraists. Due to the secret nature of the school, and because the mystery religions of Late Antiquity were persecuted by the Christian Roman Empire from the 4th century, the details of these religious practices are derived from descriptions, imagery and cross-cultural studies. "Because of this element of secrecy, we are ill-informed as to the beliefs and practices of the various mystery faiths. We know that they had a general likeness to one another". Much information on the Mysteries come from Marcus Terentius Varro.
Justin Martyr in the 2nd century explicitly noted and identified them as "demonic imitations" of the true faith, and that "the devils, in imitation of what was said by Moses, asserted that Proserpine was the daughter of Jupiter, and instigated the people to set up an image of her under the name of Kore" (First Apology). Through the 1st to 4th century, Christianity stood in direct competition for adherents with the mystery schools, insofar as the "mystery schools too were an intrinsic element of the non-Jewish horizon of the reception of the Christian message". Beginning in the third century, and especially after Constantine became emperor, components of mystery religions began to be incorporated into mainstream Christian thinking, such as is reflected by the disciplina arcani.
The English word 'mystery' originally appeared as the plural Greek Mystêria, and developed into the Latin mysterium where the English term originates. The etymology of the Greek mystêrion is not entirely clear though scholars have traditionally thought it to have derived from the Greek myo, meaning "to close or shut" (chiefly referring to shutting the eyes, hence, one who shuts their eyes and is initiated into the mysteries). More recently, a number of Hittite scholars have suggested that the Greek term derives from the Hittite verb munnae, "to conceal, to hide, to shut out of sight".
Mystery religions formed one of three types of Hellenistic religion, the others being the imperial cult, or the ethnic religion particular to a nation or state, and the philosophic religions such as Neoplatonism. This is also reflected in the tripartite division of "theology"—by Varro—into civil theology (concerning the state religion and its stabilizing effect on society), natural theology (philosophical speculation about the nature of the divine), and mythical theology (concerning myth and ritual).
Mysteries thus supplement rather than compete with civil religion. An individual could easily observe the rites of the state religion, be an initiate in one or more mysteries, and at the same time adhere to a certain philosophical school. Many of the aspects of public religion such as sacrifices, ritual meals, and ritual purification were repeated within the mystery, but with the additional requirement that they take place in secrecy and be confined to a closed set of initiates. The mystery schools offered a niche for the preservation of ancient religious ritual.
Though historians have given up trying to outline a rigid definition to categorize all mystery cults, a number of characteristics that the mystery cults shared can be outlined. All the mystery cults placed emphasis on the secrecy of their practices and an emotional initiation ritual for a new member to join the group. The members were voluntary participants, had nocturnal settings and preliminary purifications for their gatherings, there was an obligation to pay in order to participate, promised rewards for this life and the next, and the older mysteries were located at a variable distance from the nearest city. Furthermore, they were all, with the exception of the Mithraic cult, open to all people, including men and women, slaves and freeman, the young and old, etc. However, the expenses required to participate in all the rituals often precluded many from joining. And though the mysteries were secret, they were not very mysterious. 
For this reason, what glimpses we do have of the older Greek mysteries have been understood as reflecting certain archaic aspects of common Indo-European religion, with parallels in Indo-Iranian religion. The mystery schools of Greco-Roman antiquity include the Eleusinian Mysteries, the Dionysian Mysteries, and the Orphic Mysteries. Some of the many divinities that the Romans nominally adopted from other cultures also came to be worshipped in Mysteries, for instance, Egyptian Isis, Persian Mithras from the Mithraic Mysteries, Thracian/Phrygian Sabazius, and Phrygian Cybele.
The Eleusinian Mysteries were the earliest and most famous of the mystery cults and lasted for over a millennium. Whenever they first originated, by the end of the 5th century BC, they had been heavily influenced by Orphism, and in Late Antiquity, they had become allegorized.
In the 15th of the month of Boedromion (September/October) in the Attic calendar, as many as 3,000 potential initiates would have gathered in the agora of Athens, the gathering limited to those that spoke Greek and had never killed (as the emphasis on purity grew, this ban would include those who had "impure" souls). Like other large festivals such as the Diasia and Thesmophoria, the prospective initiates would bring their own sacrificial animals and hear the festivals proclamation as it began. The next day, they would have gone to the sea and purified themselves and the animals. Three days of rest would pass until the 19th, the agora was once more filled with the initiates at the procession at the sanctuary of Demeter and her daughter Persephone. Two Eleusinian priestesses were at the front of the procession followed by many Greeks holding special items in preparation for the rest of the ceremony, and the procession would leave the city on an hours-long 15-mile journey constantly interrupted by celebration, dances, etc, to the city of Eleusis. The initiates would carry torches on the way to the city. Once the city was reached, the pilgrims would dance into the sanctuary. The next day would begin with sacrifices, and at sunset, the initiates would go to a building called the telestêrion where the actual initiations would commence. The initiates washed themselves to be pure and everyone sat in silence surrounded by the smell of extinguished torches. The initiation may have taken place over two nights. If so, the first night may have concerned the myths of the kidnapping of Persephone by Hades in the Homeric Hymn to Demeter (where Persephone is kidnapped and her mother, Demeter, searches the earth for her, and once her daughter was returned, Demeter promised prosperity in this life and the next) and ended with Persephone's return and the guarantee of fertility, whereas the second night concerned the epopteia (the higher degree of the Mysteries) which was a performance that included singing, dancing, potentially the showing of a phallus, a terrifying experience for the audience by the skilled Eleusinian clergy, and the climax of the event which must have included displaying a statue of Demeter and showing of an ear of wheat and a "birth" of agricultural wealth. Hence, these mysteries had associations with fertility and agriculture. In an attempt to solve the mystery of how so many people over the span of two millennia could have consistently experienced revelatory states during the culminating ceremony of the Eleusinian Mysteries, numerous scholars have proposed that the power of the Eleusinian Mysteries came from the kykeon's functioning as an entheogen.
The day of the completion of the initiation was called the Plemochoai (after a type of vessel used to conclude a libation), and the new members could now wear a myrtle wreath like the priests. Eventually, the initiates would leave and utter the phrases paks or konks, which referenced the proclamation of a conclusion of an event. The new members used their clothing in the journey as lucky blankets for children or perhaps were given to their sanctuary.
The second most famous Mysteries were those on the island of Samothrace and promised safety to sailors from the perils of the sea, and most participants would come to be initiated from the neighboring regions. While the information here is even more scarce than that available with the Eleusinian Mysteries (and more late, dating to the Hellenistic and Roman periods), it's known that the Samothracian Mysteries significantly borrowed from the ones at Eleusis (including the word 'Mysteries'), furthermore, archaeological and linguistic data continues elucidating more of what happened at Samothrace. These rituals were also associated with others on neighboring island such as the mysteries of the deities of Cabeiri. Philip II of Macedon and his later wife Olympias were said to have met during the initiation ceremony at Samothrace. Heracles, Jason, Cadmus, Orpheus and the Dioscuri were all said to have been initiated here. The deities at Samothrace tended to be anonymously identified, being referred to as the "Samothracian gods", "gods of Samothrace","Great Gods", etc. This makes it difficult to reconstruct who they were, though they were often compared to the Cabeiri.
Unlike at Eleusis, initiation at Samothrace was not restricted to a narrow few days of the year and lasted from April to November (the sailing season) with a large event likely taking place in June but may have taken place over two nights. Like in Samothrace, the future initiates would enter the sanctuary of Samothrace from the east where they would have entered into a 9-meter in diameter circular space with flagstones and a grandstand of five steps now called the Theatral Circle. Livy records that here, the initiates would listen to a proclamation concerning the absence of crime and bloodshed. Near the beginning of the rituals, like at Eleusis, sacrifices and libations were likely made, where the prospective animal for the sacrifice would have been a ram. The initiates would have moved to a building where the actual initiation took place at night with torches, though archaeologists are unsure of which building it was considering the abundance of possibilities including the Hall of Choral Dancers, the Hieron, the Anaktoron and the Rotunda of Arsinoe II. In the 3rd century, Hippolytus of Rome in his Refutation of All Heresies quotes a Gnostic author who provides a summary of some of the images here;
There stand two statues of naked men in the Anaktoron of the Samothracians, with both hands stretched up toward heaven and their pudenda turned up, just as the statue of Hermes at Kyllene. The aforesaid statues are images of the primal man and of the regenerated, spiritual man who is in every respect consubstantial with that man.
The scarcity of information precludes understanding what went on during the initiation, though there may have been dancing such as at Eleusis associated with the mythology of the search for Harmonia. At the end of the initiation, the initiates were given a purple fillet. There was also a second night of initiation, the epopteia where the "usual preliminary lustration rites and sacrifices" took place though not much else can be known besides that it may have been similar to the epopteia at Eleusis and would have climaxed with the showing of a great light.
The initiation of the first night was concluded by banqueting together and many dining rooms have been uncovered by archaeologists in association with the cult at Samothrace. The bowls used for the libation were also left behind, revealed by the thousands of discovered libation bowls at the cult sites. The participants occasionally left behind other materials, such as lamps. In addition to the purple fillet, they also left with a 'Samothracian ring' (magnetic iron ring coated in gold) and some initiates would set up a record of their initiation in the stoa of the sanctuary. The initiation of the second night was also concluded by a banquet.
Other mystery schools
- Cult of Despoina– An Arcadian cult worshipping a goddess who was believed to be the daughter of Poseidon and Demeter.
- Cult of Attis– A Greek cult that was not followed in Rome until its early days as an empire. It followed the Story of Attis, a godlike figure who was eventually killed by a boar sent by Zeus.
- Cults of Cybele– A number of cults following Cybele, or Magna Mater, were present in Greece, Anatolia, and Rome. This cult followed Cybele, which was an Anatolian "mother goddess". However, after it became present in Rome, the Romans reinvented Cybele as a Trojan goddess. In Rome, the cults of Cybele were often restricted and gained few members because of strictures against castration, which was considered a ritual necessary for initiation. This was later replaced with animal sacrifice, but numbers were still limited.
- Mysteries of Isis– This was a rather present and more well-known cult. While most of the mystery cults revolved around Hellenistic culture and religion, the cults of Isis worshipped the Egyptian goddess of wisdom and magic. It emerged during the Hellenistic Era (323 BCE through 30 CE).
- Jupiter Dolichenus
- Cult of Trophonius– A Hellenistic cult surrounding a minor god/hero. A number of people went to his temples to receive and oracle.
- Dionysian Mysteries– This was a small cult with unknown origins. It is believed to have pre-dated Greece and possibly originated from Crete or North Africa. Its rituals were based on a theme of seasonal life and rebirth.
- Mithraic Mysteries– One of the more famous Greco-Roman mystery cults. They follow the story of the god-hero Mithras. One of their more distinct features would be the underground structures in which they worshipped, all of which had a mural or sculpture of Mithras killing a sacred bull at the entrance.
- Orphism– Another of the more famous mystery cults, this cult followed the story of Orpheus, a mythical poet who descended to the underworld and back. A number of the mythology associated with Orpheus is also relating to Dionysis, as mentioned above.
- Cult of Sabazios– This cult worshipped a nomadic horseman god called Sabazios. He was a Thracian/Phrygian god, but the Greeks and Romans interpreted him as a mixture of Zeus/Jupiter and Dionysus.
- Cult of Serapis– A cult following the Greco-Egyptian god Serapis. He and his cult gained a decent amount of popularity in Rome, causing him to replace Osiris as the consort of Isis outside of Egypt. He was worshipped in processions and sanctuaries.
Influence on Early Christianity
Modern scholars reject simplistic notions of dependence of Christianity on the mystery religions. Towards the end of the 19th century and beginning of the 20th century, it was becoming more popular in German scholarship to connect the origins of Christianity with heavy influence from the mystery cults, if not labeling Christianity itself as a mystery cult. This trend was partly the result of the increasing growth of critical historical analysis of Christianity's history, as exemplified by David Strauss's Das Leben Jesu (1835-6) and the secularizing trend among scholars that sought to derive Christianity from its pagan surroundings. Scholars, for example, began attempting to derive Paul's theology from a Mithraic mystery cult in Tarsus, even though no mystery cult existed there nor did a Mithraic mystery cult exist before the end of the 1st century. The attitudes of scholars began to change as Egyptology continued emerging as a discipline and a seminal article published by Arthur Nock in 1952 that noted the near absence of mystery terminology in the New Testament. While some have tried to tie the origins of rites in Christianity such as baptism and the Eucharist to mystery religions, it has been demonstrated that the origins of baptism rather lie in Jewish purificatory ritual and that cult meals were so widespread in the ancient world that attempting to demonstrate their origins from any one source is arbitrary. Searches for Christianity deriving content from mystery religions has also been unsuccessful; many of them (such as the mysteries of Eleusis and Samothrace) had no content but rather limited themselves to showing objects in initiation.
The studies of modern scholarship reveal that while Christianity was not a mystery religion, it was compared to them by various opponents of the early religion, such as Lucian and Celsus. Most early Christians, including Justin Martyr, launched attacks against the mysteries. Justin also compared Christianity to pagan religions, however scholars have criticized Justin for the shallowness of his comparisons. On the other hand, once Constantine became emperor of the Roman Empire and legalized the Christian religion, Christians lost their fear of pagan persecution and some concepts from the mystery religions, for the first time, became mainstream in Christian thought.
- Crystal, David, ed. (1995), "Mystery Religions", Cambridge Encyclopedia of The English Language, Cambridge: Cambridge UP.
- Barnes, Ernest William. The rise of Christianity. Longmans, Green and Company, 1947, 50-51.
- Bromiley 1995, p. 451.
- Puhvel 1984, pp. 188-192.
- Johnson 2009, pp. 98-99.
- Bremmer 2014, p. XI.
- Bremmer 2014, pp. 1-20.
- Webster, P. (April 1999). "The Road to Eleusis: Unveiling the Secret of the Mysteries. Twentieth Anniversary Edition, by R. Gordon Wasson, Albert Hofmann, Carl A.P. Ruck, Hermes Press, 1998. (Originally published by Harcourt Brace Jovanovich in 1978). ISBN 0-915148-20-X". International Journal of Drug Policy. 10 (2): 157–166. doi:10.1016/s0955-3959(99)00012-2. ISSN 0955-3959.
- W. Greenwalt, ‘Philip II and Olympias on Samothrace: A Clue to Macedonian Politics during the 360s’, in T. Howe and J. Reames (eds), Macedonian Legacies (Claremont, 2008) 79–106
- Bremmer 2014, pp. 21-36.
- (ed.) Patte, Daniel. The Cambridge Dictionary of Christianity. Cambridge University Press, 2010, 848-849.
- Lease, Gary. "Mithraism and Christianity: borrowings and transformations." Aufstieg und Niedergang der römischen Welt 2 (1980): 1306-1322
- A.D. Nock, Essays on Religion and the Ancient World, 2 vols (Oxford, 1972) 2.791–820
- Bremmer 2014, pp. 142-164.
- Peregrinus 11
- Against Celsus 6.24; see also 3.59
- Bremmer, Jan (2014). Initiation into the Mysteries of the Ancient World. Walter de Gruyter. ISBN 9783110376999.
- Bromiley, Geoffrey (1995). The International Standard Bible Encyclopedia. Eerdmans. ISBN 9780802837851.
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- Alvar, Jaime. Romanising Oriental Gods: Myth, Salvation, and Ethics in the Cults of Cybele, Isis, and Mithras (Leiden, 2008).
- Aneziri, Sophia. Die Vereine der Dionysischen Techniten im Kontext der hellenistischen Gesellschaft (Stuttgart, 2003).
- Bowden, Hugh. Mystery Cults of the Ancient World (Princeton, Princeton UP, 2010).
- Bremmer, Jan N. Initiation into the Mysteries of the Ancient World (Berlin, 2014).
- Burkert, Walter (1987), Ancient Mystery Cults, Cambridge, Massachusetts
- Casadio, Giovanni Casadio and Johnston, Patricia A. (eds), Mystic Cults in Magna Graecia (Austin, TX, University of Texas Press, 2009).
- Media related to Mysteric religions in ancient world at Wikimedia Commons