Buddhism is essentially Aryan and based on dharma. as I said in an earlier thread on Julay, the Chinese Communists consider Buddhist Tibet to be feudal and bourgeois, which to me is an excellent endorsement.
Zoroastrianism is not bad in and of itself, but it's the first link on the Abrahamic chain, and had much influence on Judaism/Christianity/Islam.
Gnostics believe that the physical universe around us was created by the Demiurge, a being who ranges from amoral to evil. he is not God, but believes he is, because he's cut off from the spiritual world while still being a derivative of it. our souls are from the spiritual plane, but are ensnared within the material plane, which is the central conflict of human existence. the Gnostics rely on esoteric knowledge and insight to attain liberation and ascension.
Manichaeism regards our universe to be a mixture of light and darkness, as a result of primordial battles between these two forces. while there are similarities, this should not be confused with Gnosticism, as the belief systems are quite distinct.
ultimately, Gnosticism has roots in Neo-Platonic philosophy and Christianity. it was Plato who first posited the demiurge, a being derived from a higher power who fashioned the physical universe. however, he sees this entity as benevolent, and as a rational explanation for existence, without the spiritual conflict.
Manichaeism seems to be a pastiche of religion as it existed in Late Antiquity. you have the material/spiritual clash of Gnosticism, the duality of Zoroastrianism, the Judeo-Christian Messiah, and the structure of hearers/elects is very similar to Buddhist monasticism. there are probably other influences woven in as well.