How can you comare the concepts of the crusades to in the modern day era

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. Two major effects of the Crusades were that the kings' authority increased and the Europeans learned about new things from the Muslims they encountered. During the Crusades, the kings increased taxes to fund the cause. Many peasants also left their land to fight, and when they died, the land went to the king.