In 1208 the Inquisition was established. Seven years afterward, the fourth council of the Lateran enjoined all kings and rulers to swear an oath that they would exterminate heretics from their dominions. The sword of the church was unsheathed, and the world was at the mercy of ignorant and infuriated priests, whose eyes feasted upon the agonies they inflicted. Acting, as they believed, or pretended to believe, under the command of God; stimulated by the hope of infinite reward in another world — hating heretics with every drop of their bestial blood; savage beyond description; merciless beyond conception, — these infamous priests, in a kind of frenzied joy, leaped upon the helpless victims of their rage. They crushed their bones in iron boots; tore their quivering flesh with iron hooks and pincers; cut off their lips and eyelids; pulled out their nails, and into the bleeding quick thrust needles; tore out their tongues; extinguished their eyes; stretched them upon racks; flayed them alive; crucified them with their heads downward; exposed them to wild beasts; burned them at the stake; mocked their cries and groans; robbed their children, and then prayed God to finish the holy work in hell.
Millions upon millions were sacrificed upon the altars of bigotry. The Catholic burned the Lutheran, the Lutheran burned the Catholic, the Episcopalian tortured the Presbyterian. the Presbyterian tortured the Episcopalian. Every denomination killed all it could of every other; and each Christian felt in duty bound to exterminate every other Christian who denied the smallest fraction of his creed.
Robert Green Ingersoll – “Heretics and Hericies”(1874)