How did the Jesus movement fare after Constantine the Great? After his death in 337, Constantine's sons governed the empire, with Constantine II in the west; Constantius II in Constantinople; and the youngest, Constans, in the central prefecture, composed of Italy, Africa, and Illyricum. Challenges to the brothers' rule from outside pretenders eventually left Constantius II (the namesake of Constantine's father) the sole ruler of the empire.

Constantius II was strongly Arian in his Christian preferences, resisting the first draft of the Nicene Creed, but also attempted to enforce reforms based on Christian doctrines, like outlawing magic and dismantling pagan temples. One account says that he called a church council in A.D. 360 (which is not recognized by the surviving church) to issue a revised, Arian, creed. And apparently, after visiting Rome and seeing the continued splendor of that city's pagan temples, he lost his enthusiasm for dismantling them. His reign from 337 until his death in 361 is one of the longest of any Roman emperor.

Constantius II was succeeded by Julian the Apostate, a cousin of Constantius as the son of a half brother of Constantine. One of his first acts after succeeding Constantius II was declaring his strong commitment to paganism, and he began disenfranchising the Christians and undoing their gains since Constantine's edict of toleration. He died just two years after Constantius II, in a battle with Persians on a canal between the Tigris and the Euphrates rivers.

Jovian (Flavius Iovianus in Latin, c. 332–364) was a soldier and a Christian the army selected to succeed Julian, but he ruled less than a year, dying from an accidental asphyxiation. Valentinian, who the army also chose, ruled for eleven years in the west (from Milan and cities in Gaul), and after his succession appointed his brother Valens to rule the east from Constantinople.

Valentinian was succeeded by his son, Gratian, at nineteen years of age. He, in turn, appointed Theodosius I to rule the east on the death of his uncle Valens in A.D. 379. Under Gratian, who was counseled by Bishop Ambrose of Milan (the first bishop so popular that he could be seen as a threat to the government), pagan practices were curtailed and orthodox Christianity dominated the entire empire for the first time.

Rebel generals assassinated Gratian in 383, after which Theodosius I, ruling in Constantinople, emerged as the most powerful Caesar. He also turned out to be the last emperor of the entire empire, east and west, was the one to declare Christianity the state religion, and called the First Council of Constantinople in A.D. 381 to ratify the First Ecumenical Council, fine-tune the Nicene Creed, and finally settle the Arian controversies.

The Eastern Empire, though marked as the unified empire had been by ups and downs, expansions and contractions, continued for another millennium, until the fall of Constantinople under Constantine XI to Ottoman Sultan Mehmed II in 1453. While the pope of Rome became the figurehead successor of the western caesars (as the primary focal point for western European cultural integration and progress), the Eastern Orthodox Church, under its equal and independent bishops (though not officially separate from its western counterparts until 1054), continued to make spiritual progress.

Second-Longest Surviving Empire

The Byzantine or, more properly, the Eastern Roman Empire, under Orthodox influence and tutelage, is one of the longest-lasting empires in world history. If it is considered as the successor of the Roman Empire (as most historians would), the Roman Empire lasted just twenty years fewer than the Chinese Empire founded in 221 B.C. by Qin Shi Huangdi, which lasted until 1279.

The leader of the Bulgarian Empire claimed the title czar (also spelled tsar and tzar), meaning caesar, when it had a victory over the “Byzantine” Empire in A.D. 913. Ivan IV of Russia also appropriated it for himself in 1547, and some Russian Orthodox promote the claim that Russia succeeded Byzantium as the next embodiment of the spirit of the Roman Empire. This claim may be an attempt to promote the patriarch of Moscow, the leader of the world's largest Orthodox church, as the rightful Orthodox hierarch deserving the place of highest honor among Orthodox bishops, but as long as the Russian Orthodox remain in communion with the ecumenical patriarch in Istanbul, they can't press that case very far. And there's little evidence to support Moscow's claim that, since the rise and fall of the Soviet Union, it has the largest membership in the Orthodox world.

Piety of Nicholas II

The biographies of the last czar of Russia, Nicholas II (who was executed with his family in Yekaterinburg by the Bolsheviks), leave little doubt that he was a successor in the tradition of religious Byzantine emperors. His biographers say he and his czarina Alexandra were pious Orthodox believers, and that he was motivated because of his convictions to abdicate his throne, believing it was the best thing for his people when the Communists overthrew his government.