In our diagram, Christ and the devil appear as equal and opposite, thus conforming to the idea of the “adversary.”
This opposition means conflict to the last, and it is the task of humanity to endure this conflict until the time or turning-point is reached where good and evil begin to relativize themselves, to doubt themselves, and the cry is raised for a morality “beyond good and evil.”
In the age of Christianity and in the domain of trinitarian thinking such an idea is simply out of the question, because the conflict is too violent for evil to be assigned any other logical relation to the Trinity than that of an absolute opposite: In an emotional opposition, i.e., in a conflict situation, thesis and antithesis cannot be viewed together at the same time.
This only becomes possible with cooler assessment of the relative value of good and the relative non-value of evil.
Then it can no longer be doubted, either, that a common life unites not only the Father and the “light” son, but the Father and his dark emanation.
The unspeakable conflict posited by duality resolves itself in a fourth principle, which restores the unity of the first in its full development.
The rhythm is built up in three steps, but the resultant symbol is a quaternity ~Carl Jung, CW 11, Para 258.