In 1184, Pope Lucius III issued a papal bull, Ad Abolendam, to combat the Albigensian heresy in southern France. They were known as Cathars, or Good Christians. They were going around doing horrible anti-Christian things – like saying killing was bad, being vegetarian and treating women as equals was good, and that the church was too rich. The Pope decided they had to be stopped. How? In the words of the army commander he sent to them: ‘Kill them all. God will recognise his own.’