Religious person originated this:
Caedite eos. Novit enim Dominus qui sunt eius
(Kill them. For the Lord knows who are His.). That is the origin of the modern phrase: “Kill them all and let God sort them out.”
Controversey over what was actually said but was attributed to the Cisterian abbot Arnaud Amalric replying about the Albigensian Crusade. Prior to the attack on Béziers he had been asked how to distinguish Cathars from Catholics.
Wipe them all out, root and branch, down to the last generation. Leave no stone on top of another and slat the earth or the Jewish people and the State of Israel will eventually cease to exist.