I am not certain but I think the various popes of the Medieval time period converted just about all of Europe if it wasn't already converted before then.
The pope was the most powerful man in medieval Europe.
Medieval Europe, not just the bishops, followed Christianity, in the form of the Catholic religion, those head was the Roman Pope.
With the pope but some power went to the counts as well.
Pope Innocent III was the most powerful pope of Medieval times.
Charlemagne believed in the unity of the Christian church, and he saw himself as the defender and protector of the faith. He also believed in the importance of education and cultural revival, supporting scholars and promoting learning throughout his empire. Additionally, he believed in the expansion of his kingdom and played a key role in consolidating the Frankish territories in Europe.
The Pope was a powerful figure because of the position he held. The Roman Catholic Church was thought of as controlling you for all eternity, so you would want to respect its leader!
All of them pretty much.
Pope
The King, Pope and some medieval countries had emperors.
The Pope's role in the Medieval society is to represent the spiritual authority of the Church and, later, the state authority, which was normally represented by a King or Emperor, but was changed with the argument titled the 'Doctrine of Swords', which claimed that the Pope had authority over both the church andthe state.
The current pope (2013) is Pope Francis.
Pope and church to some extent, but in the late middle ages the kings often fought the Pope and ignored him.