The nothingness acts as an invisible unreal power only through its attraction and, by the fears of man, receives a borrowed existence. Evil arises in the souls which are trapped in matter and weakened by the attraction of nothingness.
Crusade against Christians
Blanca was the mistress of Laurac, a feudal fief in the Lauragais, a region that was considered an epicentre of heresy during the Inquisition. She was a devout Cathar (une croyante) and, widowed in old age, moved with her youngest daughter into one of the “houses” in the village and lived the life of a Bonne Femme after her initiation.
As a Bonne Femme, she had the same rights and duties as her male brothers. She could become Prioress of the Maison, could preach and perform all the rites, and also give the Consolamentum. Only the office of bishop was reserved for the Bons Hommes.
Blanca had five or six children, all of whom became devout Cathars. One of her daughters and her children were involved in one of the first major trials of the Inquisition in 1238. Blanca’s fourth daughter, Guéraude, lived in Lavaur (Lauragais) and, when the place was attacked during the First Crusade in 1211, her brother, a powerful Occitan seigneur, rushed to his sister’s aid. He was cruelly murdered along with his 80 knights. His sister Guéraude has gone down in the chronicles of the Crusade as Na Geralda. She was thrown into a well and killed with a hail of stones by the soldiers of the crusade. In this attack on Lavaur, 400 Cathars were burned at the stake. 
In 1244, the pyres burned at the castle of Montségur, the last retreat of the Church of the Bons Hommes. Despite this crushing defeat, Pierre Authier (notary to the then Count of Foix), his brother, his son and some bold companions enabled a brilliant rebirth of Catharism in the county of Foix and in Toulousain until, they too, seized by the Inquisition, were burned in 1309/1310. The very last Bon Homme, G.Bélibaste, was burned in 1321.
The philosophy of Catharism
Christian spirituality in the year 1000 was altogether dualistic. It saw the world as the scene of a conflict between two opposing forces, those of good and those of evil. The monks and ecclesiastical knights were counted as good, the unbelievers and heretics as evil. Above the opposing forces there was an all-powerful God. The focus on a God who rules over good and evil, however, did not yet make it possible to answer the question: Where does evil come from? For the Cathars, the question was: How can it be that a church that wants to represent the power of God on earth persecutes and desecrates Christians?
In the 12th and 13th centuries, their scholars developed a dualistic vision whose roots they found in the Bible, especially in the Gospel of John. There it says about God and the divine Word: “All things were made through him; and without him was not anything made that was made” (John 1:3).
For the Cathars, this sentence made no logical sense. Why should the statement that all things are made through him still find affirmation in a double negation?
They found an explanation in the Jewish-Gnostic writings of the Naassenes that convinced them. The Naassenes (in the 2nd century) based their interpretation of the passage in John’s Gospel on the original Greek text, which they translated as follows: “All things were made through him, and without him was made nothingness.” 
The Cathars adopted this version in their New Testament (Le Nouveau Testament Occitan, a copy of which is preserved in Lyon) in Occitan: sans lui es fait nient. 
It became one of the foundations of their absolute dBoth in Italy and in Occitania, absolute dualism received a philosophical imprint in the middle of the 13th century. Due to the development of theology at the first universities in Europe (especially in Italy) and the science of scholasticism taught at them (a scientific-methodical reasoning oriented towards Aristotelian logic), Cathar scholars began to rationalise and philosophically present the often confused imagery of Gnostic mythologies. Unfortunately, these philosophical writings have been lost, except for very few works.
Probably the most important philosophical writing of the Cathars is The Book of Two Principles (Liber de duobus principiis) by Giovanni di Lugio, who became bishop of the Cathars of Desenzano (Lake Garda) around 1250. 
The book of the two principles
Absolute dualism assumes two opposing principles that are operative during the divine process of creation. Underlying these two principles are two different substances of being: the absolute divine all-good being and the absolute nothingness or non-being. Nothingness is already present at the beginning of creation. It is not evil. This only arises later, in the souls trapped in matter and weakened by the attraction of nothingness.
The interrogation of a Cathar before the Inquisition in the county of Foix in 1320 hints at how simple believers experienced absolute dualism:
“Did you ever have a teacher who taught you the articles of faith you have just confessed?” “No, I discovered them myself when I thought about the world. From what I perceive in it, I don’t think God created it.” 
The divine process of creation
The absolute good being
The absolute non-being
steps out of its eternal transcendent All-unity and creates the human souls through its light.
simultaneously enters the process from its absolute emptiness, thereby time comes into being.
From now on, divine creation is subject to time.
Through the temporal process, the souls experience a different density of irradiation through the divine light.
In contact with the light, nothingness acts as resistance and limitation.
The nothingness acts as an invisible unreal power only through its attraction, and by the fears of man receives a borrowed existence.
First of all, matter falls prey to this attraction, since it contains the lowest fullness of being, and all elements are brought into disorder. This drags many souls with it, who become confused, connect with matter and thereby sin.
Thus arises the world of mixed being – a mixture of being (melange) of good and evil. God’s creation is still imperfect.
When light mixes with darkness, it makes the darkness shine. But when darkness mixes with light, the light becomes dark and is no longer light. It is sick. (Apocryphon of John)
“Understanding the good”
– this was a phrase the Cathars uttered to discreetly make themselves known to each other during the time of persecution. 
It was this right understanding of the good that Giovanni di Lugio was concerned with in his work. He stated:
“Since many people are prevented from recognising the real truth, I have resolved to enlighten those who have an understanding of it. To reassure my soul, I expound the true faith by the testimonies of the Scriptures and by true arguments, having first invoked the help of the Father, the Son and the Holy Spirit.” 
Di Lugio explains that God can work in his creation in several ways:
Firstly, he can intensify his power of being in the souls who long for him, so that they can resist nothingness.
Furthermore, in cooperation with man, he can transform evil into good through the power of opposites. He can make his grace work, and he can reveal to man the truth, the divine radiation, which is laid down as good news in the Gospels. God fights in man himself when he serves him. Man’s prayers and rites are sacrifices that God needs to transform evil into good. God needs man to perfect his creation.
And finally, as Di Luigio points out, God gains power over time through his eternity by making reincarnation possible for the human soul. Through the suffering that man experiences, he can become aware of nothingness and gain the power to transform.
All human souls will be saved one day, according to Giovanni di Lugio’s message. Even the souls of the inquisitors …
“In Catharism there had been something that did not go out with the funeral pyre” (Jean Duvernoy). 
 Anne Brenon, Cathares – La contre-enquete, p. 75 ff
 Michel Roquefort, La religion cathare, Paris 2009, p. 277
 Ibid., p. 279
 In addition to absolute dualism, there was also a “moderate dualism” among Cathars that approximated Catholic teaching. It attributed the creation of the world to a fallen angel. This angel had risen up against the almighty God and had held human souls captive in this world ever since. In the middle of the 13th century, however, absolute dualism became more and more prevalent.
 Renè Nelli, Ecritures cathares, Monaco 2011, p. 75-185
 Michel Roquebert, op. cit.
 Anne Brenon, Dico des Cathares, a.a.O., p. 82/83
 Renè Nelli, La Philosophie du catharisme, Paris1975
 Jean Duvernoy, La religion des Cathares, Toulouse 1989