An unbelievably painful history.
Ukrainians are Catholic. Russians are Russian Orthodox.
Ping.
To georgia girl - that's not correct. The religious difference between Ukrainians, Russians and Bialorussians is slight, just as the language difference is slight. The reason is that they are all Orthodox Eastern Slavs derived from Kievan Rus - with the Russians taking after the Mongol Khans, the Bialorussians after the Lithuanians and the Ukrainians as a frontier between Catholic-Orthodox-Islam.
the very people of Ukraine are mostly East Slavics who moved away from the Moscow dominated serfdom and the Polish dominated Commonwealth
When Left bank Ukraine (west of the Dnieper) came under Polish-Lithuanian domination it was mainly Orthodox, but due to the prestige of Polish, most of the lords and nobility became Polonized (ie started speaking Polish, became Catholic -- this indicates how little difference there really is between the slavic peoples)
Later under the treaty of Breszcz, the Uniate church was formed to make sure the peasants stayed loyal to the commonwealth (because Moscow at that time was playing the "we will reunite the Rus i.e. the Orthodox East Slavs together under the Grand Duke of Moscow"
But after the Commonwealth was torn apart, there was forced Russification and that went hand in hand with destroying the Uniate Church
Today ukraine is a nation that was aborted still-born. it never had the chance to distinguish itself from its neighbours and still does not. Pessimistically I believe it is too late for the nation to be born.