Mithraism, the ancient worship of Mithra, the Iranian god representing the sun, justice, contracts, and warfare, played a significant role in pre-Zoroastrian Iran. In the Roman Empire, during the 2nd and 3rd centuries CE, the deity was revered as the protector of loyalty towards the emperor. However, as Christianity gained acceptance under Emperor Constantine in the early 4th century, Mithraism experienced a swift decline.
Prior to the reforms of Zarathustra, also known as Zoroaster, in the 6th century BCE, the Iranian people practiced a polytheistic faith, wherein Mithra held a position of paramount importance among the gods. He was fundamentally associated with oaths and mutual obligations. For instance, a cuneiform tablet from the 15th century BCE referencing a treaty between the Hittites and the Mitanni highlights Mithra’s invocation as the deity of vows. Similarly, in Indian Vedic literature, the god Mitra embodies concepts of friendship and contracts, showcasing that mutual obligations are foundational to friendship. Essentially, Mithra symbolizes any form of positive human interaction and the bonds fostering good relations among individuals.
Mithra was regarded as the Mediator and also identified as the god of the sun—symbolizing the illuminating force that observes all things—including commitments made between rulers and their warriors, thus linking him to warfare. Moreover, he represented justice, which was upheld by the sovereign. The observance of justice and treaties was often a mark of reverence towards Mithra. A key ceremonial practice in Mithraism was the sacrifice of the bull, which has drawn debate regarding its origins—whether it was pre-Zoroastrian or not. Given that Zarathustra condemned such sacrifices, it is likely that this ritual belonged to the earlier Iranian pagan traditions. Evidence from Indian texts supports this connection, portraying Mitra as participating reluctantly in sacrificial rites involving a deity named Soma, represented as a bull or the moon. Roman depictions of Mithra show him performing the reluctant sacrifice of the bull, who transforms into the moon, suggesting this rite predated Zoroastrianism.
The bond between contracts and sacrificial rites is noteworthy, as ancient treaties were often celebrated with shared meals. Following Darius the Great’s reign (522–486 BCE), the Achaemenid dynasty embraced Zoroastrianism. Nevertheless, these kings did not seek to dismantle the enduring beliefs of the nobility, leading to a gradual amalgamation of Zarathustra’s doctrines with older polytheistic practices. Hymns, called Yashts, were composed in honor of the traditional deities, including one dedicated to Mithra—a portrayal of him as the vigilant deity of celestial light, guardian of oaths, and protector of righteousness, opposing the forces of evil and darkness.
By the later Achaemenid era, Zoroastrian elements notably overshadowed pagan practices. The bull sacrifice, despised by Zoroastrians, is notably absent in later references. The conquest of the Persian Empire by Alexander the Great around 330 BCE seemingly led to the disintegration of the established religious practices surrounding Mithra. However, local elites in the western regions of the former empire continued to honor him. Notably, the Armenian king Tiridates, upon accepting Roman Emperor Nero’s sovereignty, conducted a Mithraic ceremony, symbolizing the god’s role in fostering amicable relations between Armenia and Rome. In Commagene (southeast Turkey), Mithra was likewise worshiped, and Mithradates VI of Pontus may have been one of his followers, as indicated by the practices of his allied Cilician pirates in 67 BCE.
Despite this, the worship of Mithra did not gain popularity in the Greek territories, primarily due to the associations with the Persians. Awareness of the Persian deity in the Roman context appears sparse until the 2nd century, after which numerous inscriptions honoring Mithra emerged starting in 136 CE. This resurgence remains somewhat enigmatic; the prevailing theory suggests that Roman Mithraism evolved into a reformation of the Persian traditions, potentially crafted by an influential figure around 100 CE, who integrated Platonic philosophy to render the ancient ceremonies relatable to the Romans. Similar to its Iranian roots, Roman Mithraism was characterized by loyalty to the emperor, receiving support from various emperors like Commodus, Septimius Severus, and Caracalla, with many dedicated followers being soldiers and influential officials.
Mithraic altars and dedications proliferated throughout Rome, Ostia, military frontiers, and regions throughout Britain, the Rhineland, the Danube, and the Euphrates, though they were rare in peaceful areas. In those instances, dedications typically came from governors or officials. Over generations, Roman society fully integrated this once-Iranian deity into its cultural fabric. Even Diocletian’s attempts at rejuvenating Roman religion and state affairs acknowledged Mithra, as seen in a dedication in 307 CE near Vienna, where Mithra was honored as the empire’s patron.
Yet, the tides shifted dramatically in 312, when Constantine triumphed at the Milvian Bridge under the Christian cross, resulting in a definitive halt to Mithraic dedications, despite the absence of an explicit prohibition against its practices. While there were sporadic dedications between 357 and 387 CE, these chiefly stemmed from the old pagan elite in opposition to the Christian regime in Constantinople. In these instances, Mithra appeared as one of many ancient deities. Ultimately, the Mithraic mysteries waned considerably, folding into obscurity as pagan worship came to an end in the face of rising Christianity.
