No! You do not get to choose bishops, I do as the pope!
I would like you to meet, my new bishop, Sir Canes.
No! This is unacceptable! I choose bishops! Not you!
How dare you try to get rid of me!! I am Pope, in charge of YOU!
After Pope Gregory declared authority of the secular and nonsecular leaders, King Henry became angry. He wanted the power to choose his own bishops, so he did. This made Pope Gregory really mad.
Yes, he is not being what a good Christian ruler should be so actions need to be done.
After Pope Gregory chose his own bishop, King Henry was exasperated. They both wanted to have the power to choose their own bishops. This caused much conflict between the two.
What! Oh no! You can't! What are you doing?!
King Henry unsuccessfully tried to remove Pope Gregory as a pope. This made Pope Gregory mad, of course, so he will try to get rid of King Henry once and for all. Pope Gregory needs to claim his power over everyone, for he is, after all, the pope.
Why can't I choose my own bishop?
50 years later with a new king and pope
Pope Gregory will have King Henry excommunicated. This means that King Henry will not be king anymore, and that he cannot participate in Church activities. The pope does not care if the king will be mad because he is far too superior in his own sense.
King Henry, of course, was fuming at this sudden banishment. He was so angry at Pope Gregory, who also freed his subjects from their oaths of loyalty to the king. King Henry thought that he was more superior to the pope, and the pope thought the same, but Pope Gregory did excommunicate King Henry from the Church.
Although the conflict between Pope Gregory and King Henry subsided when they died, this fighting went on for many years after them. In 1122, peace was supposedly put on between the Holy Roman Empire and the Church, called the Concordat of Worms. This did not work because they continued to have conflicts.