Conflict between the Christian and Muslim world is not a recent issue. These two cultures have clashed many times in the years of their existence. After the inception of the Muslim faith by Mohammed, Islamic members aggressively sought out converts to their new religion through the Middle East and Northern Africa. Christians performed the same task centuries before when Christianity was declared legal by Constantine in 324 AD
The first major worldly clash between these two cultures occurred during the crusades. The crusades lasted for the better part of 2 centuries. A total of 7 crusades were established. Most people and historians focus on the first 4 crusades. The last 3 crusades were shells of the desire and focus of the first four.

The first crusade was created in 1096 AD, and lasted until 1099 AD. The origins of the crusades started with the passage of European pilgrims entering the Holy Land of the Middle East. A difficult situation occurred in this area, all three major religions laid spiritual claim to the cities, especially Jerusalem. Most Christians did not live in the Middle East, but rather traveled from Europe. Jewish people could be found in both Europe and the Middle East. Muslims lived in the Middle East.
Muslims felt that the pilgrims were ungrateful visitors to the Holy Land. The pilgrims were not respecting the customs and laws of the Muslim world and looking down on the current tenants. Besides differences in religion and law, there was little similar to the two cultures in terms of way of life and social customs. It was just a bad mix. Muslims were not permitting Christians the right to enter the Holy Land. There were instances of violence at this point. The word came back to the current Pope of Christianity, Urban II. Outraged, the Pope calls for the defense of the Holy Land from the Muslims. In turn for defending the Holy Land, Pope Urban II forgave the sins of the warriors. This inspired people to fight because now they were guaranteed passage into Heaven when they died.
Politically, there was more to the story. Prior to the Crusades, the Pope supported the expulsion of all Muslims from Spain. Also in 1054, the church split into two different bodies. The western church followed the Pope in Rome, and the eastern church sought guidance from Constantinople (Eastern Orthodox Religion). This was a way for the western church to reclaim authority in the Eastern Mediterranean region.

For an individual, the crusades promise passage into Heaven, but if you weren't ready to die, the Crusades provided a few earthly blessings. For Kings and knights, the crusades provided a new elevated status within their countries, and their regions. For the lower class, it gave men a chance to see the world and collect riches to be used upon their return to their homeland. The Crusades also provided merchants new products to provide and sell.
1st Crusade 1096-1099AD
2nd Crusade 1147-1149 AD
3rd Crusade 1189-1192 AD
4th Crusade 1202-1204 AD
The first crusade was the only crusade that was considered successful. It was a miracle that it was successful because the European Crusaders had

1. Little Military Knowledge

2. Little knowledge of Middle Eastern Geography

3. Political arguments erupted all through the Crusades

4. Poor organizational skills
The Crusades were not a military success overall, the Muslims retained the Holy Land over and over. European kings and lords turned their focus on other projects erupting on the European continent. Besides the lack of military success, the Crusades also failed to open the Holy Land up the way the Pope's wished to have it opened. Politically, the divide between the Muslim world and Eastern Europe widened. Even today, the Muslim world and Western Europe (Christianity) are at odds.

The Crusades were a success because Western Europe learned many new things about the Muslim world and way of life. Trade routes were also established, and this brought new products to Europe as well as in the Middle East. At this point, Europe wished to find new trade routes and increase profit on the continent.