Greek Apostasy fact or fiction?

Part of the Chronicles of Russian, and, the rest of, Christian history -- brought to us in English by "Medieval Russia's epics, chronicles, and tales" -- a 16th century manuscript, recording the Christian prophesy, of how Rome was destined to fall, move to Byzantium -- establishing Christian Rome; which, destined to fall into heresy, would subsequently, be established in Russia as the third and final Rome.