Cathars believed that the "Old Testament God" --—the creator of the physical world --- was Satan. Every material thing, including the human body, was, they said, created by this evil god; making more of it (e.g. procreation) was considered wicked, and forbidden. This was the antithesis to the monotheistic Catholic Church, whose fundamental principle was that there was only one God, who created all things visible and invisible, and which He declared good.
The persecution of the Albigensians was shameful -- much of it was indisputably murder. My only point is that they were not Protestants, unless "Protestant" is elasticized to mean "anybody believing any kind of dingbattery so long as it's not Catholic."
Pretty much Vlad's manta...