What are some of the reasons that the crusades began?

Question

Please explain the answers.

Answer 1

Territorial issues... Also, Pope Urban supposedly began the crusades in 1095 as a test of his political ability. Some say he wanted to secure the papacy a strong position in global affairs and politics.

Answer 2

To the Christians of Europe, Jerusalem in the Holy Land was a sacred city. The tomb of Christ, the Mount of Olives, Golgotha, and all places associated with the life and death of Christ were believed to have divine powers of healing and of absolving penitents of sin. People from all parts of Europe made pilgrimages to Jerusalem and other holy places.
As long as the Saracens held Jerusalem, there was very little trouble. The Saracens permitted the pilgrims to come and go. In 1071, however, the fierce Seljuk Turks captured Jerusalem from the Saracens. The Turks at once began to persecute the Christians. Pilgrims on their way to the Holy City were robbed and beaten. The sacred places of the Roman Catholic church were profaned or destroyed.
When European Christians heard of the persecution, they were outraged. Alexius Commenus, emperor of the Eastern Roman Empire, feared that the Turks might seize Constantinople, his capital. They had already defeated and slain his predecessor. As the terror of the Turks spread, Alexius Commenus sent a plea for aid to Pope Urban II at Rome.
The pope called a council at Clermont in France in 1095. Speaking with ringing eloquence, he urged his audience to undertake a crusade to rescue the Holy Land. No speech in history has ever had greater results. Fired with religious zeal, clergy, knights, and common people shouted, "God wills it!"

Answer 3

Christians were fighting Muslims for the city of Jerusalem which is a religious symbol for both (it is where Christ was crucified in Christianity, and where the prophet Muhammed ascended into heaven (I think, not really up on Muslin beliefs))

Answer 4

You would really have to look at the Papacy, or the "Dark ages."