When the patriarch of Moscow died in 1700, Peter I left the office vacant, and in 1721 abolished it. In its place he created the Most Holy Governing Synod, a committee of bishops operating under a chief procurator who was a layman appointed by the tsar, an arrangement borrowed in part from Lutheran state church practice and one that lasted almost two hundred years. The clergy became, in effect, civil servants: they kept the registers of birth, marriage and death, read state decrees from the pulpit, and were required to report seditious matter disclosed in confession.
The church had already been split before this. The liturgical reforms imposed by Patriarch Nikon in the 1650s, correcting Russian books and gestures against Greek usage, were rejected by a large body of clergy and laity who became the Old Believers, and who were anathematised, taxed, exiled and in some communities driven to mass self-immolation rather than submit. They were not granted legal toleration until 1905.
Catherine II secularised the monastic estates in 1764, transferring vast lands and their peasants to the state and closing more than half the monasteries. Kallistos Ware's history notes the paradox of the period: an institutionally subordinated church that nonetheless produced the eighteenth and nineteenth century revival of hesychast spirituality, the Philokalia in Slavonic, the elders of Optina, and Seraphim of Sarov.