If Horus / pseudodionysus is a Christ-form, then (the Greek) Atë is the antagonist.
A challenger of the true-evils of self: pride, vanity, malice, etc; Atë renders a close approximation to the role of a satan.
‘satanism’ would not be the opposite of gnosticism. A satan is the Obstructor, not the obstructed.
Gnosticism’s opposite may be the ‘plain fool’, but not the archetypal Fool, but neither might we ascribe it as Ignorance. Ignorance is absent of the willfulness shown by Zeus (in the Atë myths).
Willful Ignorance is thus the special conjugate of Gnosticism. This is “Blue Pill” stuff, in today’s vernacular. If we take to the legal history of such a personal state, then we can find reasonable the language that such a person acts in “bad faith.” Where we know, here, that “faith” is not a religious article, but a self-knowledge (gnostic) concept.
Acting in bad faith, one may be considered fundamentally Reckless — if again, we take Gnosis to be authentic universal knowledge apprehended through the self.
Thus perhaps, one who acts in the opposite of Gnosticism — is a Liar.