What do you think you're doing in my castle! I am the one who rules this country.
I am the one who has the most power here. I control the church.
I am claiming authority over both church and secular leaders
You have too much power!
I am also declaring myself to have the power to choose bishops.
You can't do that!
When Pope Gregory arrived in 1073, he had many strong ideas about how the king held the power, or the pope held the power. King Henry was the King of Europe when Gregory was pope and they had debates over who held the most power in Europe. All of the conflicts between kings and popes started when Pope Leo believed that the when Charlemagne became Emperor, the church made him Emperor and not God which led to a clash between kings and popes.
King Henry will never have power when I remove him from being the emperor.
Are you sure you can do that?
When Pope Gregory issued the rule that he had power over both church and secular leaders, King Henry responded with anger as he felt threatened by the pope. King Henry was furious and was almost about to remove Pope Gregory from being the pope. King Henry did not threaten him enough to remove Pope Gregory from being the pope. Then the Pope Gregory created rule that went against the King Henry.
Please forgive me Pope Gregory.
You may have committed many wrongs, but I'll forgive you.
When Pope Gregory declared that he had power over both church and secular leaders, he also declared that he could choose bishops for the king. With the pope able to choose bishops, King Henry ignored the rules and named his own bishop for the city of Milan. Pope Gregory responded by appointing a rival bishop for King Henry which drew power away from the king.
We agree on the Concorodat of Worms!
After Pope Gregory had authority over secular and church leaders and the ability to choose bishops, he claimed the power to remove emperors from the throne. Obviously, Pope Gregory removed King Henry from the throne after he claimed he could remove emperors from the throne. There was only so little for King Henry to do at this point since Pope Gregory appointed a rival bishop, had power over church and secular leaders, and he removed King Henry from being the emperor.
Lastly, Pope Gregory excommunicated King Henry which means to remove a person from the church or religious community which made him almost the lowliest person in Europe because he had no power. The pope also freed King Henry's subjects from their feudal oaths of loyalty to the emperor. Once King Henry had no power, he apologized to Pope Gregory and the pope forgave him and then King Henry marched his army to Rome and forced the pope out of office.
Finally, in 1122, the Church of the Holy Roman Empire reached an agreement to stop the argument between who held the power called the Concordat of Worms. The Concordat of Worms gave the church the authority to appoint bishops and the emperors the ability to give fiefs to bishops in order to win their loyalty. Even with this agreement, kings and popes still continued to argue about who held the power even after King Henry and Pope Gregory died.