Zwingli, Luther and Calvin found political protectors with the power to use the wedge issues of these theologians to shatter Christendom."
If we set aside numerous strictly religious issues -- indulgences, simony, communio sub utraque specie, marriage of priests, liturgical languages, non-biblical doctrines such as Purgatory, biblical questions of salvation by works over grace, etc...
If we set all that aside, and focus just on worldly politics, then the Protestant Reformation was all about breaking the stranglehold of power exercised by the Bishop of Rome over the political community loosely known as "Christendom".
The Roman Bishop's worldly political (as opposed to spiritual) powers were inherited from traditions first established under Roman Emperor Constantine (center) and the Council of Nicaea in 325 AD.
