From the blog Icons and their Interpretation a post entitled "The Eyes Have It: The Westernization of Russian Icons in the 17th Century."
First, in its middle, came the huge controversy in the Russian Orthodox Church over revisions in ritual (such as how to make the sign of the cross) and in liturgical books. Patriarch Nikon, the head of the Church, thought that the way the Greeks did things at that time was the correct model to follow, and that the Russian Church had deviated from what he thought was that standard. On the other hand, conservative traditionalists were furious over that uppity Nikon wanting to change the way their fathers and grandfathers and great-grandfathers had done things, and saw Nikon as a dangerous heretic. How dare he say that the spelling of Jesus should have an extra letter! How dare he change the way everyone had always crossed themselves, saying that the fingers had to be in the position used by those deviant Greeks, who, after all, had their civilization destroyed for their evil ways when God punished them for their heresies by allowing the Moslems to conquer Constantinople, the Second Rome, in 1453!
In short, there was a tremendous schism in the Russian Orthodox Church, and it separated into two main divisions: first, that of the conservatives who firmly maintained the old ways of doing things, and second, that of the State Church that had the punishing authority of the Tsar behind it. As a consequence, the Old Believers — the “Old Ritualists” went one way, and the State Church, persecuting those they considered to be raskolniki — “schismatics” went another...
Complete post here.