In the medieval perspective, the denial of one doctrine in Christianity amounted to a denial of the whole of Christendom. To deal with divergent doctrine, the Church conceived of two roles for herself: 1) convert the heretic, and 2) protect Christian society. The question was, How far should and would she go to protect society? Was violence ever a justifiable option to secure peace? In the 13th century, a “yes” to the latter question came in the Inquisition.
The Inquisition, which means “investigation” or “to inquire into”, began as an institution to root out hideaway heretics and witches. The 4th Lateran Council in 1215 allowed for the punishment of heretics and in 1252 Pope Innocent IV authorized torture to force information from a suspect. The tortures and executions involved burning, drowning, and other methods. While the Church had attacked heretics through the Middle Ages, the Inquisition introduced guidelines for investigation and punishment to the process.
One heresy that bore heavily in the launch of the Medieval Inquisition was Catharism, also called Albigensianism because it greatly influenced Albi in South France. According to its enemies, Catharism upheld a Gnostic perspective, whereby the material is bad and the immaterial is good; avoided marriage, sex, meat, and material possessions (consider against its Gnostic stance); belief that matter and spirit were engaged in a cosmic civil war; and Christ as a messenger of God, a life-giving spirit, and a teacher of the right way, but not as a resurrect savior. By the close of the 1400s, maybe even the early or mid-1300s, the Inquisition had crushed the spread and popularity of this group.
The Church so fiercely opposed heretics, i.e. those who did not conform to the articles of faith that they espoused, because they believed that their existence threatened society and would undermine the Church. Through the medieval period the Catholic Church had gradually gained much power both as a religious institution and as a force in secular affairs. When Martin Luther inadvertently launched the Protestant Reformation, the Christians who adhered to his Lutheran/Protestant doctrine came under the fire of the later Roman Inquisition because their ideas challenged Catholicism.
The concern about heresy was certainly not without warrant. In the 4th century Constantine’s conversion turned Christianity vogue invited laymen to the Church who “converted” for political motives rather than out of genuine spiritual conversion. In addition, the unification of the empire brought peoples from Christian and heathen backgrounds together, so pagan beliefs infected the Church. From A.D. 325 to A.D. 787 the Church held seven major ecumenical councils to address heresies like Arianism, Nestorianism, and Docetism, and settle Christ’s humanity and divinity, the Trinity, and other Christian doctrines. In those centuries, as the Church found its footing in the post-apostolic world, the elimination of heresy and establishment of common creeds was essential for survival.
Pope Gregory IX launched the Medieval Inquisition in the 1200s to, in addition to maintaining the authority of the Church, likewise guard against supposed anti-Christian beliefs that could decompose church unity.
During a period of general religious unanimity in Europe, the Inquisition was an approved method of combating heresy. In modern times, however, fierce persecution against non-conformists would appeal to very few given the valuation, at least in Western countries, of each citizen’s right to practice his or her own religion, not to mention that torture and the threat of death rarely creates genuine converts.