The Crusades were quite instrumental in changing Europe. As the Crusades ultimately failed in the ultimate goal—the taking of the Holy Land, many monarchs did not blindly follow Vatican orders. This would centuries later lead to the Reformation and a separation of church and state in many locations.
Secondly, the Crusades weakened the power of the Byzantine Empire. In 1204, crusaders sacked Constantinople. While the Byzantine Empire would exist for over two hundred years after this, it is important to note that this act proved that there was little good feelings between Western Europe and their fellow Christians in Constantinople. The fall of Constantinople would ultimately be Europe's gain in that intellectuals from the former Byzantine Empire would spur an interest in the Classics that would ultimately lead to the Renaissance. Also, the closing of the Oriental trade routes to Western Europeans would ultimately lead to the search for a water route to China, thus leading the the Age of Exploration and the rise of imperial Europe.
Thirdly, the Crusades led to the expansion of European's horizons. Many Europeans returning from the Crusades desired the same spices that they ate in the Holy Land. This led to an increase in the market for spices and would fuel interest in European trade with Asia.
The Crusades had many direct and indirect consequences for Europe. While it is possible that Europe might have undergone secular changes without them, the Crusades were a catalyst in getting Europeans to think outside of terms of "Christendom."