The Gnostic core belief was a strong dualism: that the world of matter was deadening and inferior to a remote nonphysical home, to which an interior divine spark in most humans
aspired to return after death. This led them to an absorption with the Jewish creation myths in Genesis, which they obsessively reinterpreted to formulate allegorical explanations of how humans ended up trapped in the world of matter. The basic Gnostic story, which varied in details from teacher to teacher, was this:

Archons Hidden Rulers Through the Ages