Why was the Roman Catholic Church the most powerful religion during the Middle Ages?

During the Middle Ages, the Roman Catholic Church was the most powerful religion. The majority of Europe during this time was Catholic. Most Catholics refer to this time as the"Age of Faith". I preferably call it the"Age of Ignorance". Why was the Roman Catholic Church so powerful during these times? What caused it to become this way all throughout Europe? ------

When the Roman Empire accepted christianity as the Empire's main religion, most of the populace converted. There were certain perks as officals had to be christian etc etc. Now remember that the Roman empire had two capitals: Rome and Constantinople (West and East). Even as the West was invaded and pillaged, don't forget that christian missionaries were going out and converting people inside and outside the empire.

But that didn't stop the attacks that happend in the West. Long story short, as Rome was invaded different parts of the empire started fending for themselves creating their own states. When the invading tribes began occupying Italy instead of pillaging them, the people were still christian, and over time, the tribes became christian.

So throughout the "dark ages" the only common aspect in europe between Countries was that the people were christian. So whereas a king was leader of a small country, the Christian church with the major western seat in Rome opposite the other major cities in the Eastern empire, were the most powerful organization in all of Europe. Their authority was greater than that of any king in that time.
All christians were under the same universal church until the 11th century when the Bishop of Rome tried to gain more political power by essentially saying his seat held greater authority than the other Bishops in the East. The East did not recognize that so the West became the Roman Catholic church and the East were the Orthodox.

Shortly thereafter you have the Pope sanctioning other kings or dukes to conquer others who did not submit to the Pope. The prime example of this is the Duke of Normandy known as William the Conquerer who invaded England in 1066 A.D. and did the forced conversion and destruction of the Orthodox churches there. It was truely the first crusade. The Pope having consolidated his rule in the West then urged Roman Catholic Europe to invade the Holy Land in 1095 A.D ....and the rest is history as the Pope headed the biggest and most powerful organization in Europe until it was challenged by the Protestants. And their power went on the decline ever since.