The 12th century was an era of religious awakening: The great piousness and the desire to live like the first Christians did in times of the Primitive Church, led to a movement of voluntary poverty that was particular borne by hermits and itinerant preachers as at the end of the 11th century. In some cases these roots resulted in new monastic communities or independent orders, which is demonstrated by the acceptance of the Dominicans and Franciscans by the Church in the 13th century. Some of these wandering groups and preachers, however, had views that were different from the doctrines of the Catholic Church or criticized the Church strongly. Arnold of Brescia, for example, a reformist and scholar of the famous Paris philosopher Abelard, was imprisoned and executed in 1155 with the help of Frederick I Barbarossa because of his harsh criticism of Church and Papacy. Only the groups that integrated into the structures of the official Church, could avoid denouncement in the long term.

At the beginning of the 1140s, the Church was particularly concerned about one heretical group that had spread across France, the western part of the Empire and northern Italy – the Cathars. In their way of life they were similar to the supporters of the Christian poverty movement, but their dualistic belief did not conform to Catholic dogmas. According to their view, the material world was created by Satan and evil, exactly as a body that incarcerated the heavenly soul of angels. In order to free the soul from this prison and to be able to return to heaven, Cathars rejected materialism. The first reports about this group came from Cologne: In 1143, the provost of a local Premonstratensian abbey wrote to Bernard of Clairvaux that heretics, who despised everything worldly, did not eat anything stemming from procreation, rejected sexuality, also within marriage, whose leaders calling themselves prefects followed very strict ascetic standards, had been captured and burned. With the ideals poverty, modesty and abstinence, the Cathars reflected the spirit of the times and were popular amongst all sectors of the population. It was especially dangerous for the Catholic Church that Catharism was not just a loose affiliation of people, but it comprised a hierarchical organisation which made it into a kind of Antichurch. That is why the Cathars were fought in different ways, e.g. crusades against them were called in the 12th century, sympathizers were threatened with tough punishment, and finally at the beginning of the 13th century, the Papacy initiated the Inquisition. After their organisation was destroyed, the last Cathars disappeared at the beginning of the 14th century.

Hildegard of Bingen, who was always well informed about the happenings through her numerous correspondence and the central location of her monastery, certainly soon learned about the spreading of the heretical streams. During her preaching journeys she also came to Cologne, where a group of Cathars had been burned in 1163, as well as in 1143. In her sermon she described her opinion about the heretics who she, due to their – according to Hildegard only superficial – friendliness, abstinence and their impeccable way of life, were considered as very dangerous. The news about this sermon also made its way to Mainz, where they were keen to know what Hildegard thought „about the heresies of the Cathars“. She fulfilled this desire and sent a letter to the cathedral town: „They are the ones who deny the divine origins, i.e. that God created everything and commanded it to germinate, grow and develop“. Hildegard saw in the Cathars the pioneers of the devil and advised the people to expel the „impure and unholy people“ before they could seduce them. Hildegard not only condemned the Cathars, but also rebuked clerics who no longer supported the Church and were a negative example for the people in their quest for wealth and vanities.