Tsardom
“the varied forms of service... to the tsar and the fatherland are an image of the main service to our heavenly King, which must continue forever.”* – St. John of Kronstadt, author of religious book
Moia Zhizn’ o Khriste (My Life in Christ) and the archpriest of the Russian Orthodox Church
Demography is destiny. In the 22nd century European deathbed demographics have turned the continent over to the more fertile Orthodox Slavs. Atheism in Europe has been exterminated. Homosexuals are hanged, stoned or crucified. The remaining Catholic and Protestant populations are relegated to serfdom**, a form of second class citizenship. They are denied arms, denied civil rights, denied a voice, and are specially taxed. Their sons are taken as conscripted soldiers while their daughters are subject to the depredations of the continent's new masters.
In that world, Petra, a German girl separated from her family and sold in a business transaction between two Slavic neo-nobles at the age of nine, dreams of escape. Unlike most serfs of the day, Petra can read. And in her only real possession, her grandmother's diary, a diary detailing the fall of European civilization, Petra has learned of a magic place across the sea: America. But it will take more than magic to free Petra and Europe from their bonds; it will take guns, superior technology, and a reborn spirit of freedom.
* - I feel really uncomfortable using a Saint’s quote in such context

. But it was the closest I could find to a historical quote from a an Orthodox figure that could be misinterpreted as supporting serfdom in the given context.
** - Yes, I know serfs made up the majority of the population in Russia, not the minority. But I figured that in the 22nd century most of the hard labor historically done by serfs could be relegated to robots while other menial and embarrassing jobs can be relegated to oppressed religious minority serfs