As of 2024, Russia is around 62% Christian, 21% Atheist, 10% Muslim and 1.4% belonging to other religions (the rest were undeclared), Whereas ethnically it's only around 70% Russian. (Source: Wikipedia)
And to my knowledge it's not like Russia was historically any more tolerant towards minorities than most Western European states. Indeed, Russian history is also no stranger to mass ethnic cleansing, as the Circassians and Crimean Tatars can attest.
And yet, you still have places like Dagestan, Tatarstan, Chechnya and many other regions in Russia where Russians and Orthodox Christians are themselves a minority. This is in stark contrast to say Western Europe, which has historically basically been 100% Christian and isn't nearly as ethnically diverse.
So why is this the case? Were the minorities in Russia somehow more resistant to persecution, or did the Russian State itself functioned in way that it couldn't completely assimilate ethnic or religious minorities?