The New Crusade?
In the 13th Century, the Catholic Church waged a 'Crusade' against a competing Christian sect known as Cathars (ref: Albigensian heresy, Albigensian Crusade, Zoe Oldenbourg's books on the period and subject matter, etc.) in the south of France, primarily in the Langedoc region.
The person chosen to head this 'Crusade' (or, 'Holy War', Christian-style) was Simon de Montfort of (Holy Land) Crusader fame. He headed an 'army' composed of mercenaries, fortune-seekers, religio/military veterans and (in general) some of the rankest scum of Europe at the time. The Albigensian Crusade was, in effect, 'state/church' sanctioned genocide, and succeeded in wiping out most of the province, culminating (subsequent 'mop-up' operations notwithstanding...) in the massacre at Mont Segur.
When de Montfort and his 'army' came to the town of Toulouse (I think it was Toulouse...one of the cities in that area, at any rate) he sent word in to the city fathers to 'hand over' any Cathars and/or sympathizers to be burned at the stake for heresy...failure to do so would result in de Montfort's total destruction of the town and the 'putting to the sword' of every living creature in it.
The city fathers refused. (There was much intermarriage of Catholic and Cathar, and the two affiliated populations had lived in enviable peace and harmony together for upwards of a hundred years, by then.) De Montfort then ordered the city and 'every living creature in it' put to the torch and sword. When even his own lieutenants protested that he was condemning hundreds of innocent people, 'good Catholics' among them, to a hideous fate, de Montfort is reputedly quoted as saying, "Kill them all. God will know his own."
The use of a version of this quotation, by military personnel in Vietnam as a sort of 'second coming' for the sentiment is perhaps understandable, but no more reasonable.
To contemplate a third resurrection of this phrase as the battle cry of a 21st Century Western ('holy'...?) war against terrorism, or anything else, makes my skin crawl. I think we've had just about enough of the Jihad, crusade, holy war justifications. There is nothing 'holy' about terrorism, regardless of who conducts it or what their stated motivation/justification may be. It is simply ugly, vicious, hateful and inexcusable.
Make no mistake I share everyone's feelings/reactions/impulses of anger, sorrow, and the thirst for some sort of 'balance'...whether that be in forms of justice, vengeance, or conciliation. I fervently pray, however, that we remember the moral/ethical/rational 'line' that supposedly separates 'us' from 'them', and do not let the tide of emotion and outrage carry us across it.
The blood of innocents stains enough hands already.