Gnostic systems of thought are typically described as dualistic – meaning that the world consists of two functioning entities that are entirely different from one another. Furthermore, these two forces (entities) must be in opposition to one another at all times. In Gnosticism, there are different systems of dualism that are found, ranging from extreme or radical dualism (in Manichaeanism) to weak or mitigated dualism (classic Gnostic movements) or qualified monism (in Valentinianism).
Radical dualism is a form of absolute dualism that posits two opposite forces that are equal to one another. In the Manichaeanism form of dualism, the Good and Evil (or Light and Darkness) are existing independently of one another. Radial dualism is the rarest form of dualism.
In weak or mitigated dualism, one of the two opposing forces in inferior to the other. This form of dualism is common in classic Gnostic movements, especially the Sethian texts. In the classic Gnostic creation myth, the world is created by an inferior god, the demiurge. Because the inferior demiurge is responsible for the creation of the material world, it is understandable that the pleroma created by the True God is radically different from the material world and is the home to the enlightened individuals. This is representative of mitigated dualism.
In both of the dualist systems discussed so far, both of the opposing forces are divine. In qualified monism, only one of the forces is considered divine. While the second force may or may not be divine, this is arguable. The Gnostic Valentinians are perhaps the best example of those that believe in a qualified monist theology. To the Valentinians, the demiurge created the world not out of any moral failing on his part, but simply due to the fact that he was ignorant of any higher beings. Valentinians argue that the demiurge was ignorant, not evil. Because of this ignorance, the demiurge was not divine (otherwise, he would have known that there was a True God and if he still would have created the material world, it would have been out of malevolence). Valentinian Gnostics have cause to treat the physical world with less contempt than those that practice Manichaean Gnosticism or Sethian Gnosticism.