I agree. My point was simply an add-on. To say that the Crusades were an aberation is true, but leaves out the undisputed fact that they were the only way Europe could be unified enough to mount a counter-attack against Islamic aggression.
This would not matter, except that the Crusades are almost always presented as an example of unprovoked military aggression by Christians. The next step, of course, is to claim moral equivalence with Islamic aggression, justification for Islamic paranoia about Christians, etc.
The world hears the current Islamic aggression compared with the Christian Crusades every day. (Bin Laden refers to us as "Crusaders" just as often as "Americans".) The Crusades are used as proof of moral equivalence in the West, and as a daily war cry in Islamic nations.
In sum, to point out only that Christianity does not sanction unprovoked aggression is basically to appologize for the Crusades, plus open the door to charges of moral equivalency. The historical context of the Crusades is almost never mentioned. But when looked at in the historical context, the entire picture changes. The Moslems were the aggressors then, just as they are today.