feudalism and the Church
When the Church turned from the Roman Empire to the nations of the West and gradually fashioned a civilization out of barbarian chaos, she earned the gratitude of kings and emperors who endowed her with vast property, although often as fiefs.
It was in this manner that the Church took its place in the feudal system.
This ecclesiastical property brought evil in its train.
Disputed ecclesiastical elections followed, with coveted church property as the bone of contention; while secular princes claimed the right of investiture of spiritual offices.
Owing to the great revenues coming from the landed estates attached to bishoprics and abbeys, members of the noblest families sought to buy these spiritual offices from the king or prince who granted the fief.
They were willing to meet every demand of their lord if they received an office from him.
Prelates holding feudal lands became governmental vassals.
The secular rulers expected the Church to share the national burdens and duties, inasmuch as she was sharing the land-grants.
The Church was in danger of becoming an annex of the State.
Instead of being a universal Church, she was threatened with separating into a number of national churches under territorial princes.
Feudalism was dragging her into a mire of secularization which culminated in the captivity of Avignon.
Pope Nicholas II, in 1059, issued a decree which took the election of the pope once and for all out of the hands of the emperor and the people of Rome, and placed it in the hands of the cardinals.
This was the first step toward freeing the Church from the control of secular power.
Pope Gregory VII, who ascended the papal throne in 1073, continued the work of reform by attacking the practise of simony, by forbidding married clergy to perform religious functions, and by depriving kings and feudal lords of their influence over the choice of bishops and abbots, evils which had resulted from the feudal system in its relation to the Church.
New Catholic Dictionary