How The Creator Being Evil is Central to Gnosticism
The evil nature of the creator is central to classical Gnosticism. Of course, there are later offshoots/modern interpretations inspired by Gnosticism that reinterpret these ideas, but we shouldn't pretend that the problem of creation was some insignificant side note.
In the Sethian creation myth, this world is the result of a tragedy in the divine realms. Sophia, in an act of desire outside the proper order of the Pleroma, brings forth the Demiurge, an ignorant and arrogant being who mistakes himself for the highest God. From there, the material cosmos emerge.
We are living out the consequences of Sophia's fall, divine consciousness/wisdom caught in the density of matter, subject to the rulers of this world and the ignorance that governs their creation.
Perhaps that is the final lesson of Gnosticism: to recognize the world for what it is, remember where we came from, and pass through this realm without mistaking it for our true home.