The biggest problem with the Cathar belief was that the did not think you needed a priest or someone else to be between you and God. That Holy Catholic Church (now twisted into the Roman Catholic Church) did not like the fact that the Cathar belief could become more dominant than what they had in place and I have read many years ago that the Cathar "heresy" was on the verge of exploding onto the religious stage as the dominant form of Christianity.
I put the dispute between the Cathars and the Roman Catholics into the same way that the various "contemporary" Christian churches and services are viewed in today's world by many mainstream "God fearing Christians". They are growing by leaps and bounds but do they hold any real substance other than touchy, feely, lovey, God is good experiences.
Personally I don't view God in that way and after many years of study I tend to hold God in what some would view as a little closer to the way the Cathay's held God. Their is a constant good and evil in the world