Marcionism is not identical to, but is related to Gnosticism. The main difference between the two is that Gnostics base their beliefs on wisdom, while Marcion based his teachings on the letters of Paul and the recorded sayings of Jesus.
Some modern scholars claim that Marcion was not a Gnostic because he rejected traditional Gnostic creation myths (usually elaborate in detail) and he did not claim to have a special secret wisdom. Gnostic religions are marked by their belief and inheritance of this secret wisdom, as it is the key to their salvation.
However, Marcionism and Gnosticism do share some tendencies. Firstly, both religions share the idea that the creator of the material world and the True God are not the same deity. Both Gnostics and Marcionites claim that that the creator of the material world was a malign demiurge. This view contributes to a maltheistic worldview, in that both the Gnostics and Marcionites believe that this material world is a place of suffering. In addition, both sects reject materialism. Naturally, this idea parallels the previous view of a world of suffering. Because nothing in this material world contributes to any good, there should be no attachment to material objects.
Both sects also believe that the True God (not the God of the Old Testament) sent Jesus as a spiritual entity to save humanity. Thus, Jesusí role in history and religion is not one of the Jewish Messiah; rather, Jesus is a revealer and deliverer of the requirements of salvation.