If a man abide not in me, he is cast forth as a branch, and is withered; and men gather them, and cast them into the fire, and they are burned." (John 15:6)
Jesus tells true believers how to kindle a fire. And lo, men gathered the unbelievers and cast them into the fire. This verse dictated the Inquisition's terrible method of execution just as the 'smite their necks' suras continue to dictate the favoured method of jihadis.