Arimanius is the name of a mysterious deity thought to be the opposite of Oromazes, the god of light, and is mentioned in five Latin inscriptions and a few Greek literary writings.
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Areimanios (with variants) refers to the Greek and Roman understanding of the Persian Ahriman in classical writings while discussing Zoroastrianism. The Latin writings that were discovered in a Mithraic setting imply the existence of a renamed or altered deity with a nearly identical name.
Plutarch, who defines Areimanios as the dark or evil side in a dualistic confrontation with Oromazes, devotes the longest chapter in ancient literature to him (for Ohrmuzd or Ahura Mazda). However, rather than the mysterious Arimanius of the Mysteries of Mithas, Plutarch was particularly portraying Persian Zoroastrianism. No matter how intimidating what are claimed to be images of him might look, it appears impossible that the name Mithras in the context of Roman Mithraism alludes to a malevolent creature.
Zoroaster allegedly identified “Areimanios” as one of the two adversaries who were the creators of virtue and evil, according to Plutarch. Oromazes was to be equated to light in terms of sensory experience, Areimanios to darkness and ignorance, and Mithras the Mediator to the middle. Offerings for warding off evil and grief were given to Areimanios.

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