Christian invaders
The very idea of Christianity as a religion is to continually adopt Jesus Christ's opinions about the world. But his opinion of violence and war is undeniably pacifistic. He even seems to advocate for absolute non-violence, even when attacked ("Turn the other cheek"). He teaches his followers to "Love your enemies and pray for those who persecute you." That's why it's ironic that the Crusades are being done in Christ's name, allegedly for his kingdom. The truth is that the Crusaders were in violation of their own religion.
The irony of Jews and Muslims working together
It's a little sad to notice that this is ironic, because it seems so obvious, but the Jews and the Muslims were living in Jerusalem together, since basically forever. When the Christians come to take over Jerusalem, they are stealing the city from two other religious communities who had already been living there. This irony is layered, but suffice it to say, the Jewish-Muslim divide is formidable, but the Christian Crusaders are truly violent.
The irony of the Kurdish savior
Saladin is a Kurd. That is to say, he is not an Arab, and yet, he ends up being the hero of the Arabic world, so much so that he is immediately elevated to a position of real political power, political power over both Egypt and Syria.
The irony of Saladin's reward
When someone does something amazing in battle, typically we give awards for that. But the Muslim world was so thrilled that someone finally defeated the European invaders in Jerusalem that they give Saladin two presents: Syria and Egypt. The irony is that those are entire nations and civilizations with their own peoples and customs and histories. In other words, they aren't objects to be given as rewards. The idea that someone should win a battle and then be king of nations is ironic.
The irony of time
Obviously, the battle over Jerusalem is not over. Today, the strife in each of these countries is still there. In Jerusalem, there are still those who treat the Muslims like they are not humans, like they don't deserve to live. There are constant terrorist attacks in Jerusalem from either side, because of this. It's as if the Crusaders are still active.
In Egypt and Syria, there are still instabilities in the government, and that is still partially because government power is awarded to people who shouldn't be given power, either because they are authoritarian, or because they aren't technically qualified for the job. In other words, time has not changed much in these nations. Much of our modern conflict is very, very old.
