Most Catholics are still blissfully unaware that bishops and popes are politicians and have been since the time of St Ambrose, a Roman provincial governor (and not yet baptized!) when he became bishop of Milan by popular acclamation in A.D. 374. A few years after that, Christianity became the state religion of the Roman Empire, and bishops became public officials. Until the end of the eighteenth century, some European bishops were secular princes in their own right. Some were Electors of the Holy Roman Empire.   
That now-vanished social order still persists in the language and comportment of some bishops.