What was the explanation for why Catharism identified the Old Testament God as Satan?

The earliest Gnostic Christians believed that the harsh, judgemental God of the Old Testament could not have been the loving, forgiving God of the New Testament. Influenced by the Greek philosophers, they decided that the world was created by the lesser God of the Old Testament, known to them as the Demiurge, and that the lower heavens and the earth were his domain. Some Gnostics believed that the Demiurge, living in the lower heavens, had actually been unaware that a greater, more powerful God lived in the higher heavens. Others believed there was rivalry between them. The higher God sent Jesus to earth in order to defeat the Demiurge.

The Cathars, who arrived in southern France during the Middle Ages, brought with them an evolved form of gnosticism. Following the Paulicians and Bogomils of earlier times, they thought that Satan was the lower God who opposed the good God. We know little of the detail of Cathar belief, because most of their writings were destroyed by the Catholic Church.

The Cathars had adapted their beliefs towards those of mainstream Christianity and, for example, had bishops, whereas the earlier Gnostics regarded the role of bishop as more than superfluous. Satan was a created being, although he took the place of the earlier Demiurge, and the high God took an active interest in his creation. They would have had no difficulty in seeing God in conference with Satan, as portrayed in the Book of Job, because one was the 'good' God and the other his adversary. That Satan cooperated with God in persecuting Job might perhaps have been explained by Satan's evil intent to deceive the higher God and weaken his rule. The Cathar Book of Two Principals (13) says Of the compulsion of God, however, the Lord himself says to Satan in the Book of Job, "But thou hast moved me against him, that I should afflict him without cause." Thus, God realises that Satan had tricked him.

James McDonald ('Cathars and Cathar Beliefs in the Languedoc') cites The Book of John the Evangelist, saying that "The law of sacrifices promulgated by Enoch and the Mosaic law are works of the devil."

A superb question Sir!

From my own studies into Catharism and the theology of Marcionism I have found that the Cathars came to identify the Old Testament God as an evil force in contrast to the Good God of Jesus in the New Testament due to their belief that the world and all matter was corrupt. This belief in "Two principles" can be considered radical dualism in the sense that they believed:

• That there is one realm of good/the soul/the True God
• & another realm that is evil/all physical matter/the evil God

The Cathar's beloved book "two principles" outlines this theology in a very convincing manner.

http://www.gnosis.org/library/cathar-two-principles.htm

It is possible that (similar to Marcion of Sinopes theology years before Catharism) they considered the apparent contradictions between the loving God of the New testament and what they read to be the vengeful god of the Old testament to be two principle powers in opposition to one another; thus concluding, like Marcion before them, that the Old testament God is the evil principle who brought about this world along with all its pain and confusion.

I have questioned how the Cathers would have discerned which texts refer to the words of which principle power? (which I have asked here:If the premise for Marcion's Two Principles (Dualism) is correct; which words in the Bible belong to the Demiurge?) Because, like you say, Satan is referred to in Job as discussing a plan with God.

During my study into the Cathars, I felt that they could on the outset justify their theology as it is a rather neat package in solving the problem of evil which all generations and denominations have strived for; the Cathars saw themselves as "Sparks of Divine in Flesh" (Romans 7:23;8:5 & Job 5:7); they no doubt yearned to be away from the flesh of this evil world (Philippians 1:21).

I also questioned the actual Cathar premise that how could there be two principle powers? One evil and one good? The only way I can imagine it (within human limitations) is that the good principle is infinitely more powerful than the evil; however He is also infinitely merciful towards the evil (love thy enemies and all that) therefore the two can exist indefinitely in this sort of theology. How the two came about would be the Cathar's theological mystery.

With regards the question: What was the explanation for why Catharism identified the Old Testament God as Satan? The answer is found in the Cathar's book of Two principles (Part IV. A Compendium for the Instruction of Beginners, section 7) which states the following about the evil principle/god and Satan/Devil:

[7] On the Evil Principle.     For this reason, in the opinion of the wise it is firmly to be believed that there is another principle, one of evil, who is mighty in iniquity, from whom the power of Satan and of darkness and all other powers which are inimical to the true Lord God are exclusively and essentially derived, as was demonstrated above and will appear below, God willing.

Therefore it is evident from the above Cathar text that they saw Satan as a being who's power derived from the evil principle; therefore not the evil principle himself, but most certainly his agent...in contrast to Christ who is the True Lord's agent.

I hope this touches on answering your question.

All the best.