During the medieval time there was once a devout Christian named Charlemagne. His goal was to improve the church so that he could thank god for his victories. To do this he ordered priests monks, and nuns to live strictly by the church's rules.
I got put on the earth to do gods job
The church is supposed to do that.
One day Charlemagne received an important visitor from the Roman empire. The visitor was Pope Leo III fleeing from the danger in Rome as people were trying to blind him and remove him from office. A few months later the pope was brought back to Rome but this time he under Charlemagne.
No! These rules are against me.
I want all these new rules!
The next year Charlemagne went to Rome to support the Pope. Then the Pope decided to crown Charlemagne. This coronation gave strengthened the power of the church in the west but the east church saw this as an insult and conflict rose on who could crown who until they completely split.
You are banned from the church!
200 years later another conflict broke out but this time it was between the Pope and emperor about there beliefs. The emperor thought god had made him in order to do gods work on earth. The Popes belief was that it was Charlemagne job to assist in the church to do gods work. These different believes led to a dramatic clash between emperor and the pope.
Then, later in 1073, a new Pope arose named Pope Gregory VII. He issued a list of rules saying that he has supreme authority over both churches, that the pope alone chooses the bishops, and had the power to remove an emperor. Henry IV did not like these rules as they were against him so a clash began between these two.
Henry IV ended up getting banned and excommunicate from the church. All of Europe too there sides while Henry visited the pope to try to end his excommunication. The pope ended up forgiving him but then the conflict continued and Henry later marched his army's into Rome forcing the pope to flee from the office. The struggle between Popes and emperors continued so in 1122 they made an agreement where they equaled out their rights called the Concordat of Worms.