Christians today can discuss whether the Crusades were in fact warranted. But any such discussion must be made under a clear understanding of what historically transpired and why.
There is a great deal of historical revisionism and hatchet jobs regarding these events which need to be utterly debunked. During the time of the Enlightenment up to recent time critics often claim that the Crusaders were Western imperialists, those who set out after land with a desire to loot. But there is a background that so many of the modern critics of the Crusades, for some reason, ignore: The history begins in the seventh century when conquering Muslim armies swept over the Middle East, North Africa, and southern Europe. One Christian land after another was mercilessly attacked and conquered by advancing Muslim armies. Vast stretches of once Christian lands were now in Muslim hands. The entire of North Africa, once solidly Christian now were under complete Islamic rule. It is important to remember that Muhammad told his followers, "I was ordered to fight all men until they say `There is no god but Allah.'" Just to show that his followers understood his words literally, it was a century after his death in which vast swathes of territory hung under the bloody sword of Islam. Under their rule there were gruesome tortures of Christian pilgrims to the Holy Land and vile desecrations of churches, altars, and baptismal fonts. It is in this light of centuries of Islamic conquest, bloodshed and tyranny that the Crusades should be viewed.
Therefore, the Crusades were not Christian wars of aggression and conquest but of recovering what was rightfully theirs. While there were, no doubt, many excesses among some of the peoples in the armies, which would clearly violate Christian teaching, so we cannot condone all their behavior. Some of it was downright sinful. And no doubt there are peace-loving peoples who call themselves Muslims. I have known some and many are kind and hospitable. But remember, when Christians do such things they act against the plain teaching of our Lord ... but Muhammad was a conqueror so the sword and forced conversions were and are an integral part of the religion itself. Sadly, what was going on in the lands then is not unlike the near genocidal conditions Christians endure in many of those lands today.
Today I was saddened that President Obama insulted Christians by comparing ISIS to the Crusaders of nearly 1000 years ago. No doubt he is simply repeating the trademark ignorance of our revisionist histories that he himself read in the classrooms. But isn't it a bit hypocritical to slam the Crusaders while, at the same time, being engaged in bombing campaigns of ISIS? is it really that much different?
So while I am not here defending everything done in the crusades was right. It wasn't. But I do believe the caricatures need to be dismantled.
Recommended Reading
God's Battalions by Rodney Stark