The main and tragic event in the 17th century was the great schism, the schism of the so-called Old Believers, who seceded from the main Church in protest against ecclesiastical reforms of Patriarch Nikon.
Nikon, pursuing the ideal of a theocratic state, attempted to establish the primacy of the Orthodox church over the state in Russia, and he also undertook a thorough revision of Russian Orthodox texts and rituals to bring them into accord with the rest of Eastern Orthodoxy.