@najmelliw,
The Wars of the Reformation were, of course, fought by those whose motives were religious. But that was long before the Thirty Years War. Although the Swedes in the army of Gustav Adolf were probably motivated by the prospect of the return of Catholicism at the time of the wars in Poland, it is important to remember that that first crop were military colonists from the borders of Scania, the southern part of Sweden controlled by the Danes. They were enrolled, equipped and trained even before what we call the Thirty Years War began. Poland was a threat to Lutherans in Sweden, but the Empire never was. As Walter points out, that war was (those wars were) also a part of the period of nation building, and, for Sweden, empire building.
Certainly not in all cases, but in many, perhaps most cases, religion is the
casus belli. The crusades may have ostensibly been about the rights of Christians in the so-called Holy Land, but the Franks who went there who really were men-at-arms, knights and noblemen went there to take land. When Popes called for a crusade against the Cathars, they were ignored--until Innocent III promised to declare the lords of Languedoc heretics and their estates forfeit (even though they were feudatories of the King of Aragon). The Franks lined up for that one then. The incidents of Christian brutality on a religious basis were pretty specific--various pogroms, of course, and real madness like the Rhineland massacres of Jews at the beginning of the First Crusade. The success of the
Reconquista in 1492 lead to the requirement for Moors (i.e., Muslims) and Jews to convert or vacate the newly created kingdom. Isabella was a fanatic, and her husband Ferdinand (definitely the junior partner in that marriage) was the pragnatist who knew they could seize the estates of those who emigrated.
All of which is why I say one should avoid the simplistic sort of crap that cj peddles around here. Every case is different, and each needs to be examined individually.
