Whatever the metaphysical position of the devil may be, in psychological reality evil is an effective, not to say menacing, limitation of goodness, so that it is no exaggeration to assume that in this world good and evil more or less cancel each other out, like day and night, and that this is the reason why the victory of the good is always a special act of grace.
If we disregard the specifically Persian system of dualism, it appears that no real devil is to be found anywhere in the early period of man’s spiritual development. In the Old Testament, he is vaguely foreshadowed in the figure of Satan. But the real devil first appears as the adversary of Christ, and with him we gaze for the first time into the luminous realm of divinity on the one hand and into the abyss of hell on the other.
The devil is autonomous; he cannot be brought under God’s rule, for if he could he would not have the power to be the adversary of Christ, but would only be God’s instrument. Once the indefinable One unfolds into two, it becomes something definite: the man Jesus, the Son and Logos. This statement is possible only by virtue of something else that is not Jesus, not Son or Logos. The act of love embodied in the Son is counterbalanced by Lucifer’s denial.
Inasmuch as the devil was an angel created by God and “fell like lightning from heaven” he too is a divine “procession” that became Lord of this world. It is significant that the Gnostics thought of him sometimes as the imperfect demiurge and sometimes as the Saturnine archon, laldabaoth.
Pictorial representations of this archon correspond in every detail with those of a diabolical demon. He symbolized the power of darkness from which Christ came to rescue humanity. The archons issued from the womb of the unfathomable abyss, i.e., from the same source that produced the Gnostic Christ.
A medieval thinker observed that when God separated the upper waters from the lower on the second day of Creation, he did not say in the evening, as he did on all the other days, that it was good. And he did not say it because on that day he had created the binarius the origin of all evil. ~Carl Jung; Psychology and Religion; Pages 173-174.