P1082:2, 98:5.1 The Phrygian and Egyptian mysteries eventually gave way before the greatest of all the mystery cults, the worship of Mithras. The Mithraic cult made its appeal to a wide range of human nature and gradually supplanted both of its predecessors. Mithraism spread over the Roman Empire through the propagandizing of Roman legions recruited in the Levant, where this religion was the vogue, for they carried this belief wherever they went. And this new religious ritual was a great improvement over the earlier mystery cults.
P1082:3, 98:5.2 The cult of Mithras arose in Iran and long persisted in its homeland despite the militant opposition of the followers of Zoroaster. But by the time Mithraism reached Rome, it had become greatly improved by the absorption of many of Zoroaster's teachings. It was chiefly through the Mithraic cult that Zoroaster's religion exerted an influence upon later appearing Christianity.
P1082:4, 98:5.3 The Mithraic cult portrayed a militant god taking origin in a great rock, engaging in valiant exploits, and causing water to gush forth from a rock struck with his arrows. There was a flood from which one man escaped in a specially built boat and a last supper which Mithras celebrated with the sun-god before he ascended into the heavens. This sun-god, or Sol Invictus, was a degeneration of the Ahura-Mazda deity concept of Zoroastrianism. Mithras was conceived as the surviving champion of the sun-god in his struggle with the god of darkness. And in recognition of his slaying the mythical sacred bull, Mithras was made immortal, being exalted to the station of intercessor for the human race among the gods on high.
P1082:5, 98:5.4 The adherents of this cult worshiped in caves and other secret places, chanting hymns, mumbling magic, eating the flesh of the sacrificial animals, and drinking the blood. Three times a day they worshiped, with special weekly ceremonials on the day of the sun-god and with the most elaborate observance of all on the annual festival of Mithras, December twenty-fifth. It was believed that the partaking of the sacrament ensured eternal life, the immediate passing, after death, to the bosom of Mithras, there to tarry in bliss until the judgment day. On the judgment day the Mithraic keys of heaven would unlock the gates of Paradise for the reception of the faithful; whereupon all the unbaptized of the living and the dead would be annihilated upon the return of Mithras to earth. It was taught that, when a man died, he went before Mithras for judgment, and that at the end of the world Mithras would summon all the dead from their graves to face the last judgment. The wicked would be destroyed by fire, and the righteous would reign with Mithras forever.
P1082:6, 98:5.5 At first it was a religion only for men, and there were seven different orders into which believers could be successively initiated. Later on, the wives and daughters of believers were admitted to the temples of the Great Mother, which adjoined the Mithraic temples. The women's cult was a mixture of Mithraic ritual and the ceremonies of the Phrygian cult of Cybele, the mother of Attis.