Moscow Russia as the successor of Byzantium (formation of a new stronghold of world orthodoxy in the 15th-17th centuries)

The fall of Byzantium (the Christian Roman Empire) in 1453, which since the conversion of Saint Constantine the Great in 312 had been considered the main and only state stronghold of Christianity, posed a most difficult problem for world Orthodoxy. By the middle of the 15th century, there was not a single independent Orthodox state left in the world: the Ottomans ruled the Balkans, the Ottomans and Persians ruled the Caucasus, the Russian principalities were divided between Catholic Lithuania and Poland and the Muslim fragments of the Golden Horde. Moreover, active Uniate propaganda from Rome led to the conversion of a significant part of the Greek and Middle Eastern Orthodox clergy to Catholicism, including Metropolitan Isidore of All Rus’. It seemed that the fate of Orthodoxy was predetermined. Deprived of its usual patron and protector in the person of the pious basileus (emperor, tsar), it would soon fall under the double onslaught of Catholicism and Islam. But this did not happen. Moscow, which had become the new spiritual center of Rus’ since the time of Saints Metropolitans Peter and Alexy, after the victory of Saint Dmitry Donskoy over Mamai steadily strengthened its military and political potential and by 1480 had finally broken its formal dependence on the Horde khans. The marriage of Grand Duke Ivan III, who assumed the title of Gosudar’ (Sovereign) of All Rus’, with the niece of the last Byzantine Emperor, Sophia Fominichna, conceived in Rome to promote the union, significantly strengthened the international authority of Moscow, which not only rejected the Uniate and heretical temptations, but also took the place of Byzantium as the new political leader of world Orthodoxy.