Vladimir's Second Choice

Needs Northern Lords. Start North Germanic Ásatrú, convert to any Muslim faith, and make every county in the "Russian Region" Muslim - and NB the wiki's definition: that's the de jure Empire of Russia PLUS the de jure Kingdom of Galicia-Volhynia, so don't stop at the empire's borders. Rurik (867) is the natural start - which means this stacks beautifully with Land of the Rus in one campaign. Consider lowering the Scandinavian Adventurers game rule if you convert while still weak (your old co-religionists take it personally), and the Evangelize to the Realm decision (unlocked by completing an Illustrious+ Holy Legend, Legends of the Dead) mass-converts counties impressively fast.