Most of the European inhabitants were Christians. All of them formed what was known as “Christianity” and the Church maintained its unity. In addition to the body of believers, the Church consisted of the clergy, which included the pope, cardinals, archbishops and bishops, abbots, priests, friars, monks and nuns. All the clergy were considered to act as guardians of the faith. The pope reserved the right of excommunication, that is, the possibility of declaring that someone was outside of Christianity and could not receive the sacraments. The Church marginalized and excluded other religions, such as Judaism, and openly fought against Islam. Since the eleventh century, the Pope, with the support of feudal lords, undertook the reconquest of the Iberian Peninsula, which was under the power of Muslim caliphates. They managed to conquer the whole of the peninsula only in 1492 AD. C. and most of the Muslims were expelled from the land.

In addition, between the 11th and 13th centuries, the different popes organized “the crusades”: armed expeditions in order to reconquer Jerusalem, in Palestine. Many Christians participated in the crusades motivated by faith, but these campaigns also created opportunities for knights to loot villages and enter into war. The Christians managed to conquer Jerusalem for some time, but they lost it again to the Muslims in 1291 and the Crusades ended.

In addition, the Christian Church persecuted those they considered heretics; that is, those who interpreted religious faith in a way other than that supported by the Church. To this end, in the 12th century the Church created the Inquisition: an ecclesiastical court that was responsible for detecting and condemning those who practiced witchcraft or other heresies. The sentences of the Inquisition Court could be very harsh: from torture to death at the stake.