The duty of the Church remained uncertain till about the close of the twelfth century. The incalculable mischief caused by certain passages in a book believed to be Divine is exemplified by the decree of Lucius III in 1184, which ordered heretics to be delivered to the secular arm for punishment, and expressly quoted John xv, 6, as authority for the infliction of death by fire. It “commanded that all potentates should take an oath before their bishops to enforce the ecclesiastical laws against heresy fully and efficaciously. Any refusal or neglect was to be punished by excommunication, deprivation of rank, and incapacity to hold other station, while in the case of cities they were to be segregated and debarred from all commerce with other places. The Church thus undertook to coerce the sovereign to persecution. It would not listen to mercy, it would not hear of expediency. The monarch held his crown by the tenure of extirpating heresy, of seeing that the laws were sharp and were pitilessly enforced. Any hesitation was visited with excommunication, and if this proved inefficacious his dominions were thrown open to the first hardy adventurer, whom the Church would supply with an army for his overthrow.”[19] Burning alive was first legalized in 1197, but it was the Albigensian Crusade which afforded the earliest opportunity on a great scale for the working out of the principle of religious persecution. This principle was gradually embodied first in the canon law and then in the secular law of Europe. The Inquisition codified and collated the various enactments into a logical system, which, having behind it the united authority of Church and State, became an irresistible engine of terrorism and tyranny.[20] The suppression of heresy was, indeed, the paramount duty of every Christian to the full extent of his power. No matter who was the guilty party--father, son, husband, wife, or sister--each must be denounced for concealing heresy; there could be no excuse. “It was an absolute rule that faith was not to be kept with heretics. As Innocent III emphatically phrased it, ‘According to the canons, faith is not to be kept with him who keeps not faith with God.’ No oath of secrecy, therefore, was binding in the matter of heresy, for if one is faithful to a heretic he is unfaithful to God.”[21]