When the Byzantine Emperor asked for help, he was expecting a few German or Norman knights to help him keep order. Not a mass army. Pope Urban V was actually fighting an antiPope at the time, and used this to drive the other papal claiment out of the Vatican (or where ever the papal palace was at the time). The mass of people that descended on the East surprised and scared the heck out the Byzantine emperor.
Also, the initial push to fight was that Islam had a sword at Europe's throat. They had already pushed through what is now Spain and were raiding southern Italy. The first few Crusades were more of a counter offensive.
But they did horrible things also. Many younger second sons went East to make a name for themselves. Many others went for spoils, or just to have fun playing whack your neighbor (a favorite sport for nobles of that time). The Catholic Church at times encourage this. There were the Northern Crusades, the crusade against the Cathars (from where the line “Let God sort them out” got its origin), and many others that were done by direct approval of Church officials.
However, it was never unanimous. There were many clerics and monks who preached against the various Crusades, some at a cost of there lives. The most famous case was St. Francis who traveled to the Sultan not to kill him, but to convert him (and he may have been partially successful). The Knights of the German Order and the other Northern Crusader knights ended up in trouble with Rome about as much as they were supported by it. Especially after Lithuania and Poland went Christian! (Kind of hard to have a Crusade against fellow Catholics, though they tried!).
So I guess what I am saying is I see both sides. Yes, the Roman Catholic Church did give sanction to some horrible crimes, but many also fought against those crimes from the inside. And the local nobles often ignored Rome and did what they wanted to without sanction, but using Rome's name. The most interesting one for me is in the New Mexico region, where you had Dominicans and Jesuits coming to blows with each other!
In short, it is a very complicated issue. And one that if you really want to study it, you can't have your Catholic or Protestant blinders on. The history is to messy to fit finly into either sides polemics.
The Crusades — excluding the horrendous sack of Constantinople and the entire debacle of the 4th one — were simply a noble war of liberation of the Holy Land, the war that achieved its objective (the Jerusalem Kingdom expired of neglect a century after Saladin agreed to the crusaders’ demands of free pilgrimage routes) and was lead with bravery and according to the norms of military conduct of the time.
One might question the unnecessary brutality of the wars of Reformation, but then one should begin by questioning the so-called reformation itself.
The Holy Inquisition in its full vigor is something modernity sorely lacks, as the scandal of pederast priests demonstrated.
When substantive arguments are lacking, attempts to defame the winning side often ensue. It is no big deal.
Oh, I realize that, by all means. It is not my intention to suggest that there was no need for defense, and I would heartily agree that defending against the Muslim horde was a dire necessity (I have said as much before).
Yours is an even handed position, and fair, to my recollection.