The elements of this religion of mixture are the following: 1) The negative presupposition, namely the destruction of the national religions by the conquests of Alexander and of Rome. The great world empires undercut the national religions.
2) The philosophical interpretation of mythology. When you read the systems of the Gnostics, you will have the feeling that this is rationalized myth. And this feeling is right.
3) The renewal of the old mystery traditions.
4) The re-emergence of the psychic and magic elements, as it appeared in the religious propaganda of the East; while the political movement went from the West to the East (Rome conquered the East), the religious movement, this great syncretistic thinking and acting which we call Gnosticism, went from East to West and conquered, at least partly, even Rome. So when you read about the Gnostics, don’t believe you know all about them; it is easy to dismiss them. It was an attempt to combine all the religious traditions which had lost their genuine roots, and bring them together in a system of a half-philosophical, half-religious character. The Gnostic groups showed many similarities and many conf licts with original Christianity.
They claim, against the public tradition of the Christian churches, to have secret traditions which are known only to the initiated; they are not public. They reject the Old Testament because it contradicts many of their fundamental tenets, especially the dualistic and ascetic tendencies. And the New Testament is not rejected but is purged. The man who did this first of all was Marcion. He tried to purge the Pauline canon. He leaves the ten main letters and the Gospel of Luke, which is most influenced by Paul. He rejects all other letters and gospels of the New Testament. Luke and ten Pauline letters, that’s enough – because there, no elements are present which contradict the basic ideas of Gnosticism.