Hence the devil remained outside the Trinity as the “ape of God” and in opposition to it.
Medieval representations of the triune God as having three heads are based on the three-headedness of Satan, as we find it, for instance, in Dante.
This would point to an infernal Antitrinity, a true “umbra trinitatis” analogous to the Antichrist.
The devil is, undoubtedly, an awkward figure: he is the “odd man out” in the Christian cosmos.
That is why people would like to minimize his importance by euphemistic ridicule or by ignoring his existence altogether; or, better still, to lay the blame for him at man’s door.
This is in fact done by the very people who would protest mightily if sinful man should credit himself, equally, with the origin of all good.
A glance at the Scriptures, however, is enough to show us the importance of the devil in the divine drama of redemption.
If the power of the Evil One had been as feeble as certain persons would wish it to appear, either the world would not have needed God himself to come down to it or it would have lain within the power of man to set the world to rights, which has certainly not happened so far `Carl Jung, CW 11, Para 252.