The thread on an Orthodox Prussia got me wondering something along the opposite lines - is there any way to create a situation where Russia proper (not Belarus and Ukraine) is equally divided between Catholic and Orthodox realms? Could, plucking examples out of a hat, Novgorod or Smolensk become the center of a Catholic Russia (Green Ruthenia or something?) while Moscow becomes the capital of Orthodox Russia?
Would Alexander Nevsky losing the Battle of the Ice be enough? Could the Teutonic Knights have kept pushing on deep into NW Russia if they'd won?