The letter from Jung to Wilson is useful to see the compassion in action that is the 12Step Programme, from the point of view of a supporter and interpreter of spiritual phenomena such as Jung was and is.
That Jung mentioned the Devil in his letter is relevant to the turbulence in the world today.
Alcohol is only a symbol, we ourselves are the problem and this is stated in the 12Step programme.
Therefore when Jung describes the yearning for alcohol as actually a yearning for Union with God, then it is this same yearning for Union that hides in the antics of the obese overeater, the frazzled and disgraced sex addict, the gambling addict spending the rent that is the same as the banker who crashes a whole bank, the world leaders who start their justifiable war.
The 12Step diagnostic approach to human self-destruction is to say that it is always a spiritual malady with a spiritual solution. Further, that when the spiritual malady is rectified, then the mental and physical symptoms of said malady sort themselves very efficiently.
There is no intellectual solution for a spiritual disease. That a mind refuses to believe that it is suffering from a spiritual infection, is simply part of the illness.
As a spiritual counsellor, my rôle is first to help a client to see their dysfunction clearly and only then to engage in treatment that is consensual with a clear diagnosis.
The Devil, mentioned by Jung, is a detail of the diagnosis, a detail that is actually part of the spiritual healing once reconnected and repaired to a holistic template of Human transformation, a transformation brought about by experiencing a conscious contact with God.