The most traumatic era in the entire history of Roman Catholicism, some have argued, was the period from the middle of the 14th century to the middle of the 16th. This was the time when Protestantism, through its definitive break with Roman Catholicism, arose to take its place on the Christian map. It was also the period during which the Roman Catholic Church, as an entity distinct from other “branches” of Christendom, even of Western Christendom, came into being.
The spectre of many national churches supplanting a unitary Catholic church became a grim reality during the age of the Reformation. What neither heresy nor schism had been able to do before—divide Western Christendom permanently and irreversibly—was done by a movement that confessed a loyalty to the orthodox creeds of Christendom and professed an abhorrence for schism. By the time the Reformation was over, a number of new Christian churches had emerged and the Roman Catholic Church had come to define its place in the new order.