The crusades didn’t work for a lot of reasons. None of which had to do with trying to eliminate Islam.
SOURCE: INTERNET:
Cause of the Crusades
The reason and cause of the crusades was a war between Christians and Moslems which centered around the city of Jerusalem and the Holy places of Palestine.
The City of Jerusalem held a Holy significance to the Christian religion. The Church of the Holy Sepulchre in Jerusalem commemorated the hill of crucifixion and the tomb of Christ's burial.
Pilgrims throughout the Middle Ages made sacred pilgrimages to the Holy city of Jerusalem and the church. Although the city of Jerusalem was held by the Saracens the Christian pilgrims had been granted safe passage to visit the Holy city.
In 1065 Jerusalem was taken by the Turks, who came from the kingdom of ancient Persia. 3000 Christians were massacred and the remaining Christians were treated so badly that throughout Christendom people were stirred to fight in crusades. These actions aroused a storm of indignation throughout Europe and awakened the desire to rescue the Holy Land from the grasp of the "infidel."
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Didn't you ever take world history?
One doesn't eliminate a FAITH, one eliminateds the followers of that faith. Ideas don't get eliminated, just the PEOPLE who follow those ideas. But, you know that.
The only way Islam could be eliminated would be to eliminate all Muslims.
Is that what you would want? I doubt it.
It THAT your goal? I doubt it.