If you live long enough, despite the flu’s best efforts, you’re bound to learn something.

For instance, in my ignorance, I always thought that the phrase “Kill ’em all, let God sort ’em out” was of comparatively recent coinage. It sounds like something U.S. Col. John “Nits Make Lice” Chivington might have said at the Sand Creek Massacre. Or maybe Lt. Col. Allen “Islam is Not a Religion” West while torturing a captive in Iraq.

But according to Charles P. Pierce, who recently took note of a New Republic piece on a fondness among the right-wing intelligentsia for the good old days of medieval Catholicism and other European niceties — “Constitutionalism, Enlightenment rationality, religious freedom, and republicanism are out. European aristocracy, crusading holy orders, and mysticism are in,” — writes Graham Gallagher — the phrase has its roots in the 13th-century papal crusade against the Cathars in southern France.

Here’s Charlie:

Back in those days, of course, Roman Catholicism had armies and its temporal power was unsurpassed. Theological disputes were conducted at the point of a sword. The crusade against the Cathars in the south of France killed more than a million people, many of whom died simply because of where they lived. It was this latter sanctified savagery that gave us the infamous battle plan explained by Arnaud Amalric, a Cistercian monk and the official ambassador from Rome to the armies arrayed against the Cathars. Before the crusaders massacred almost everyone in the town of Beziers, Amalric is reputed to have said, “Kill them all. God will know his own.”

And you thought it was an inconvenience when the Jehovah’s Witnesses came calling, brandishing their Watchtowers. Just wait until a flying squad of these new warrior monks rings your bell. I’m gonna go out on a limb here and suggest that the intellectual heirs of these ring-kissing brigands might not be fans of Tom Lehrer.