The Test Canosai

Cold January evening, 1077 year to the castle the margravine Matilda of Tuscany, the owner of Canossa, humbly approached the Wayfarer in the clothes of a repentant sinner. After long negotiations it was allowed for the first wall that surrounded the castle. Here he stood, barefoot, hungry, all day and all night.
Passed one more day and one night and another day.
Excommunicated the German Emperor Henry IV was waiting for him to take the Roman Pontiff Pope Gregory VII, who was away in Canossa castle.
Long relegated to the past times, when the head of the Church appealed to the head of the Empire: "Who am I to thee, my Lord! The dust and the mob!" Now the owner of the papal title, with lowliness of mind as it stuck to her faithful servants of the Lord on this sinful earth, could afford to wait.
How pleasant is the celebration of the winner! It warms the blood and causes the heart to beat faster. That he would stand at the bottom and will freeze, this impatient Lord, who in their pride rebelled against the decisions of the Roman Church. He forced the German bishops declare deposed him, Pope Gregory VII! Where is now the faithful barons of Henry? They did not dare to come close to the walls of Canossa.
Where signs of his Imperial dignity? It is he, the Pope, has eliminated Henry from the rule of the Kingdom of the Teutonic and the whole Italy, liberated Christians from the bonds of the oath and it was forbidden for anyone to serve him as king.
Only the Pope can depose emperors. No one dares to cancel his decision! No one can be a judge of the Pope, he judges us! Let them remember that all the enemies of the Holy see. And Henry IV wait let down another day.
Has passed and this day, and the Pope accepted the German Emperor. Revolting in the soul that has once again confirmed its dependence on the spiritual authority of the Church, promised to recognize the decision of the Pope in a dispute with the princes. But soon broke both.
It was a long and dramatic struggle. During her rebellious Emperor again excommunicated from the Church. However, the troops of Henry IV took Rome, the vicar of God on earth was forced to flee. Soon Gregory VII died. His successor on the papal throne for the third time announced Church attendance in Henry IV.
During the long years of struggle and rivalry with the Imperial power of the Church was able to take away from the secular lords many privileges, and with them a considerable sources of income.
Yes, this was the era of such power of Christianity, which, perhaps, did not know other religion. The Church has had an impact on state policy in all European countries. She started the war and arranged truce, none of unwanted marriages in the crowned families. At the behest of the Pontifical throne of thousands of people were sewn red cross on the right shoulder and went into a far Crusades, that in the name of their God, to kill and Rob other people and to die themselves in exile from wounds and disease.
Why the Christian Church have managed to achieve such power?