The Schism of the Russian Church, also known as raskol was an era of religious and social turmoil in Russia spanning roughly from 1667 to 1691, during which dissenters opposing the hierarchy of the Russian Orthodox Church appeared in great numbers, and were persecuted and suppressed by ecclesiastical and secular authorities.
The schism followed the liturgical and ritual reforms enacted by Patriarch Nikon at the behest of Tsar Alexis from 1652 to 1657, which aimed to remove all difference between the Russian rite and that of the Greek Orthodox church, from which Christianity was imported to the nation. Both Tsar and Patriarch were convinced that local practices diverged from the Greek ones due to faulty transmission and scribal errors throughout centuries of Russian parochialism. Nikon's reforms engendered much opposition in defense of traditional custom, voiced first by relatively marginal clerics such as priest Ivan Neronov, but later augmented by leading churchmen led by Bishop Alexander of Vyatka and Archimandrite Spiridon Potemkin. Tsar Alexis attempted to reconcile the controversy by convening the 1666-1667 Great Moscow Synod, where the old rite was anathemized and declared heretical, and the reformed rite was proclaimed binding for all.
As the state proceeded to enforce the resolutions, and in fact to extend its authority over the people's life to an unprecedented degree, it clashed with local autonomies and popular religion, provoking recalcitrance and resistance. Ecclesiastical hierarchs interpreted these complex and manifold reactions as deriving from a single coordinated heretical movement, which they termed as "the Schism", and set out to destroy and suppress. Draconian persecution of anything deemed "schismatic", combined with social grievances in the face of tightening state bureaucracy, traditionalist opposition to the reforms, and apocalyptic fervor which gripped the land in anticipation of the End of Days by 1666, led to massive religious dissent, social unrest, armed banditry, full-blown revolts and mass-suicide by self-immolation, through which many thousands perished in flames. The most extreme episodes of the Schism were the Siege of the Solovetsky Monastery between 1668 and 1676, and the Moscow uprising of 1682. By the 1690s, the turbulence gradually waned, as Peter the Great relaxed the persecution of nonconformists, and the apocalyptic zeal diminished as the world evidently did not end. In the following decades, the surviving dissenter communities mostly evolved into the Old Believers, a loose movement defined by rejection of Nikon's reforms, but also to more radical sectarians like the Flagellants.