Christianity reached the East Slavic lands through Byzantium. Tradition and the Russian Primary Chronicle credit Vladimir, Prince of Kiev, with adopting Orthodox Christianity for his realm in 988, after weighing several faiths and sending envoys to observe worship in Constantinople; the chronicle has them report that they did not know whether they were in heaven or on earth, and this account, however stylized, marks the formal Christianization of Kievan Rus. The new church was governed for over four centuries by a Metropolitan appointed from Constantinople.
The Mongol conquest of the thirteenth century devastated Kiev and shifted the center of Rus political and religious life northward. The Metropolitan see itself moved, first to Vladimir and then, by the early fourteenth century, to Moscow, a rising principality that cast itself as heir to both Kiev and, after the fall of Constantinople in 1453, to Byzantium, a self-image later expressed in the phrase Moscow as the Third Rome. In 1448 Russian bishops consecrated their own Metropolitan without Constantinople's approval, an act of effective autocephaly, or self-governance, formalized further when Moscow was raised to a Patriarchate in 1589 under Patriarch Job.
The church's history since has run alongside that of the Russian state, sharing its expansions, its schisms and its catastrophes, from the seventeenth century Old Believer split over liturgical reform to the twentieth century persecutions examined in the second article.