Maggie's Farm

Knights, Jerusalem, the Seljuk Turks - the history of the Crusades and the future of Islam, by Rubinstein in The New English Review. One quote:

The knights who entered combat against Muslims and pagans did so for Christian objectives. This led to a radical change in Christian thinking about war. Before the Crusades, the Church was ambivalent about killing and wounding in war. St. Augustine helped to formulate the idea of a “just war" by arguing that killing carried out in obedience to divine command or legitimate public authority did not violate the commandment "Thou shalt not kill."[14] Nevertheless, even a “just war” did not receive the Church’s wholehearted approval. A war that the Church promoted and blessed, such as the First Crusade, had been unthinkable.

Pope Gregory VII (1073-85). was the prelate most responsible for the Church’s changed attitude towards war.[15] One of his favorite quotations from Scripture was “Cursed be he who keepeth back his sword from blood.” (Jeremiah 48:10).[16] Gregory proclaimed a new type of Christian soldier-saint.[17] Before Gregory, Saint George and Saint Sebastian had become saints in spite of having been soldiers. As a result of his teachings, men became saints because they had been soldiers. The long-range consequences of this transformation remain with us to this day.