Restoration and tolerance of Paganism from Julian until Valens

Under the sole rule of Julian, 361–363

Julian was Roman co-emperor since 355, and ruled solely for 18 months 361–363.

Julian witnessed the assassination of his father, brother and other family members by the guards of the imperial palace; rightly or wrongly, he blamed this brutal act on the Emperor Constantius, who passed himself off as an outstanding Christian. The Christian faith was thus definitively discredited in his eyes. Upon becoming emperor, Julian decided to restore paganism, the ancient Roman religion, while reforming it in the hope of making it the driving force behind the empire. Julian's religious beliefs were syncretic and he was an initiate of at least three mystery religions. But Julian's religious open-mindedness did not extend to Christianity due to its belief that it had an exclusive perspective on religious truth. Believing itself to be the "only true religion", Christianity was opposed to, and fundamentally incompatible with, the more inclusive syncretism of paganism.

As Emperor, Julian sought to turn the tide in the attempted suppression of non-Christian religions. Julian allowed religious freedom and avoided any form of actual compulsion. The Christian Sozomen acknowledges that Julian did not compel Christians to offer sacrifice nor did he allow the people to commit any act of injustice towards the Christians or insult them. However, no Christian was allowed to teach or study the ancient classical authors, "Let them keep to Matthew and Luke", thus ending any chance they had of a professional career. He did not believe Christians could honestly teach subjects replete with allusions to Greek deities whose existence they denied The Jewish historian and theologian Jacob Neusner writes: "It was only after the near catastrophe of Julian's reversion to paganism that the Christian emperors systematically legislated against paganism so as to destroy it."

"In the eighteen brief months that he ruled between 361 and 363, Julian did not persecute [Christians], as a hostile tradition contends. But he did make clear that the partnership between Rome and Christian bishops forged by Constantine and maintained, despite conflicts over goals, by his son Constantius II, was now at an end, replaced by a government that defined its interests and those of Christianity as antithetical."

Religious Toleration under Jovian, Valentinian and Valens

After the death of Julian, Jovian seems to have instituted a policy of religious toleration which avoided the extremes of Constantius and Julian. Under Valentinian and Valens this period of religious toleration continued. Pagan writers praise both of these emperors for their liberal religious policies. Valentinian, who ruled in the west, seems to have only been a halfhearted Christian as he avoided attending his inaugural ceremony by twenty-four hours in order to avoid an inauspicious day (the intercalary day of the bissextile year). Valentinian and Valens granted complete toleration for all cults at the beginning of their reign in 364. Valentinian even allowed the performance of nocturnal sacrifices, which had been previously prohibited due to the attempt of some people to practice unlawful divination under the cover of the night, after the proconsul of Greece appealed to him. Valentinian also confirmed the rights and privileges of the Pagan priests and confirmed the right of Pagans to be the exclusive caretakers of their temples. Valens, who was ruling in the east, was an Arian and was too engaged with fighting against the Orthodox Christians to bother much with the Pagans. In both the west and east severe laws were once again passed prohibiting private divination. Due to the over zealousness of the populace to stop harmful divination, the haruspices and augurs began to be afraid to show themselves in public. This led the emperors to formally authorize the practice of official and lawful divination by law in 371.