Yes, it seems like the shortcoming of this chapter is that it focuses on the EVENTS of the Albigensians, not on their beliefs. In short, they were Gnostic.
The Cathars’ [albigensians] beliefs were very similar to the Celtic and Arian churches beliefs were until they were (with much resistance) absorbed into the Roman Church during the 7th and 8th centuries. The Cathars, the Arian and Celtic Churches did not believe in Jesus’ divinity, nor did they believe him to be the ‘son of God’ any more than the rest of us are, but they did believe him to be descended from King David and therefore ‘King of the Jews’.
http://theiberianseaschool.com/component/content/article/18-articles/112-the-cathars