I am finishing my study of Yuri Stoganov`s The Other God – which traces the history of religious dualism from Late Antiquity until the time of the Cathars… my impression is that we are fed too many loose ends to really get a good overview of the “phenomenon”, there is a consistent lack of a red thread in there, although it is incredibly detailed and varied, this is the books strenght, that it could be a kind of historical map of the phenomenon.
Stoganov basically redoes every step Steven Runciman, a famous “historian” of the Cathar movement, takes in his The Medieval Manichee and in terms of this its almost like a replacement with corrections and a more current and thorough perspective.
A much needed revision is the way the author consistently distinguishes between Monarchian dualism (which is the belief that evil emanates out of a created and inferior/subservient being or principle which will be dissolved or redeemed/transformed at the end of the cosmic cycle, including the assertion of two creators, two “universes” and two qualitatively and essentially different diametrically opposed to eachother, but where the other originates in the first and what proceeds from this one will be reconciled into the first) and Radical dualism (Two eternally co-existent principles which never be reconciled and which originally inhabited two completely realms, eternal struggle more or less defines being) – as well as philosophical dualism (Mind/Body etc.) versus religious dualism (Two gods, two authorities, two worlds, two ontological realms – a duality which is spiritual and essential rather than one of Spirit against Matter). He also consistently describes Catharism, Bogomilism, Zurvanism and to a lesser extent Manichaeism – without attempting to mix metaphors and describe either of these by way of sources and quotations from Gnostic sources. This is very helpful for those who seek to get an idea of what either of these were, with a basis in the studies of Gnosticism.
I haven`t made my mind up about it yet – the “best” is yet to come : A summary of the Bogomil and Cathar mythologies, which is the most detailed I have found.