[TexConfederate1861]

It was the common language of Western Christendom....not in the East..

[narses]

When the Roman Empire split jurisdictions and created the Eastern Ceasar, the language of the court was both Latin and Greek. Greek slowly predominated, but Latin remain an official language of the court for many years. You may well be right regards the Church (although I thought the Church followed the custom of the Court or vice-versa), but if so, the argument becomes even more compelling.