With a POD of your choice, have the West Slavs (Slovaks, Poles, Czechs) convert to Eastern Orthodoxy rather than Roman Catholicism.
The Germans must still be Catholic.
Bonus points if you can also make the Hungarians, and with them the Croats, Orthodox, leaving only the Slovenians as a major Catholic Slavic people.
The Germans must still be Catholic.
Bonus points if you can also make the Hungarians, and with them the Croats, Orthodox, leaving only the Slovenians as a major Catholic Slavic people.