In 'Answer to Job', Jung interprets God as a personification of the unconscious, longing to become conscious. It is essentially the same as Schopenhauer's idea. However, in Jung the unconscious Will is a positive force connected with the individuative drive of the individual as well as the collective.
So the unconscious has acquired a metaphysical status in Jung. He is indebted to William James and his notion of neutral monism. It means that the mental and the material have a common ground. Jung denotes it the unus mundus and characterizes it by the adjective 'psychoid'. Bertrand Russell also developed a form of neutral monism according to which the neutral stratum carries logical atoms such as 'above', 'between', 'below', etc. Since these relational words can be combined with numbers, his metaphysical edifice seems to chime with M-L von Franz's notion of number qualities as metaphysical primitives. After all, 'aboveness' and 'betweenness' are qualities, too.
Neoplatonism has a notion of innate ideas as psychic 'archetypoi' or 'logoi'. According to Proclus the psychic logoi are instantiations of Platonic Forms on the level of soul. There are corresponding logoi in Nature, as forms immanent in matter. Proclus says that all souls share the same logoi. Since these logoi are the principles of reality, it means that one can come to know the true principles or causes of reality by grasping the logoi. The soul carries also 'sumbola', corresponding to the divine principles of reality. They establish the secret correspondences between sensible things and divine realities.
Proclus puts accent on the psychic mathematicals as building stones of both soul and world. Number has also a qualitative sense and he analyzes their properties as the 'paternal', the 'generative', the 'perfective', the 'protective', etc.
The symbolic correspondences were central to Swedenborg who developed a highly psychological Neoplatonic system, putting emphasis on interiority. In Swedenborg, the inward heaven ('inner heaven', 'inner man', etc.) denotes the world of spirits as experienced during introspection. The notion corresponds to the unconscious. Since the world of spirits denotes a state of spirit and state of life (i.e., it's a mental and moral condition), it means that the inward heaven is metaphysically the same as the spiritual sphere. Here life is lived symbolically, while our conscious concepts acquire a symbolic shape. God, for instance, is by the spirits experienced as a shining sun. Thus, the essence of reality is life in the spirit, i.e., "psychic life". The material world is an emanation of a higher, or more inward, spiritual world. It is in the shape of a Grand Man.
Jung's metaphysics is firmly grounded in the Neoplatonism of Swedenborg, Proclus, and their forbears. To this is added Schopenhauer's ideas of an unconscious God that is evolving out of darkness. It is similar to the Neoplatonic concept of emanation. From William James derives the notion of a common ground for psyche and matter. However, since the logoi are the building stones of both psyche and matter, the notion is already present in Neoplatonism.
The conflicting paradigm of Gnosticism and alchemy does not play a big role, because Jung reinterprets these in terms of Neoplatonic psychology. In my regard, Jung belongs to Neoplatonic Christian tradition. His metaphysical and philosophical thinking does not introduce much new, but he is on stable ground. In the school of Christian Neoplatonism his most important forbears are Emanuel Swedenborg and Pseudo-Dionysius the Aeropagite (who wrote in the late fifth or early sixth century CE).
Jung, in several places, expresses his metaphysical creed as 'esse in anima' (in opposition to 'esse in re' or 'esse in spiritu'). The view that nature, as well as the human soul, is an emanation of the world-soul (anima mundi), derives from the creator of Neoplatonism, namely Plotinus (c. 204/5-270). He was the first to introduce in the Western world a notion corresponding to modern idealism (i.e. that reality is essentially mental). It has its roots in Indian philosophy, where the world-animating spirit is called Brahman. Also Schopenhauer, whose notion of a world-soul developing out of darkness and giving rise to all the worldly forms, is indebted to Eastern philosophy, Vedantic and Buddhist thinking. Marian L. Pauson ("Jung the Philosopher", 1988) places Jung's philosophy "within the inheritance of Christian neo-Platonism" (p.82). She continues:
"Granted that the metaphysics of the two philosophers [Plotinus and Jung] can be separated by the contemporary subtleties of sign theory and philosophical analysis, striking similarities remain in the two systems [...]
If we look at these metaphysical concepts in relation to Plotinian categories, we find many similarities. The One of Plotinus and the 'unus mundus' of Jung both share the same ineffable unknowable realm. The Nous of Plotinus and the archetypes of Jung likewise point to a similar intuition concerning the primordial order of "what is." The universal soul of Plotinus and the world soul of Jung, both of which involve the dynamics of creation, matter, form, and good and evil, also suggest a similar intuition of reality as process. And in both philosophical schemes evil is accounted for at this third level, namely, the realm of Soul. In the realm of Soul, Jung's God-image is a projection of the archetype of the Self and like all archetypes is paradoxical; it has both positive and negative aspects [...]
Jung was very much steeped in the Christian tradition. He may not have agreed with the old theologians who accounted for evil as 'privatio boni', he may have accounted for evil in the psychological and religious sense as the dark or shadow side of both human beings and God and thus removed the total blame for evil from conscious individuals; nevertheless, the absolute of his metaphysical system, as the hypothetical 'unus mundus', is beyond good and evil. From this perspective, little difference appears between the intuitions of Jung and Plotinus about reality and the nature of evil." (Pauson, pp.87-88)
However, Pauson says that their philosophical approaches are different in that Jung, being influenced by Kant, sees his own philosophical distinctions as subjective formulations whereas Plotinus sees no separation between the conceptual scheme and the reality which it explains. That is why Jung called his philosophy "his myth" and it explains why his discourse keeps slipping from one realm to the other (cf. p.87).
Marilyn Nagy ("Philosophical Issues in the Psychology of C.G. Jung", 1991) says that "I have identified Jung as belonging to the epistemological tradition whose most prominent members were Kant and Plato" (p.46). Interestingly, she also makes the following confession: "I will not conceal the fact that during the years while I have been working on this project I suffered greatly, seeing the concepts which once were able to contain all that I knew of the depth and mystery of human experience reduced to their place in a historical series" (p.269). Nagy concludes:
"This essay has shown that the conceptual structure of Jung's psychology is based on philosophical postulates which express an idealist and a metaphysical view of reality. Analytical psychology is a position-taking on philosophical issues of the nineteenth century. It embodies views, however, which are rooted in the search for moral values in ancient Greece and which have guided Western philosophical thinking ever since.
Because he found a 'psychological' format for idealism which could lead into the twentieth century, Jung himself became the latest in a tradition of great idealist philosophers to have a powerful influence in the culture of their times.
Though Jung never delineated a formal epistemological position it is possible, by following a developmental time line, and by studying a large number of his statements about what we know, to obtain a consistent picture of his views. Then, by examining the history of epistemological disputes, and particularly the moral issues which lay at the base of Plato's decision that true knowledge comes from within the mind, Jung's position can be matched with what philosophers have generally termed "metaphysical idealism." The immediate background of Jung's epistemology lies in nineteenth-century reaction to the new sciences, and the materialistic and positivist philosophies which accompanied the upswing of scientific influence. A certain type of radically subjectivistic neo-Kantianism was much favored at the end of the century, particularly by religionists who hoped thus to defend religious truths from the reductionist conclusions of scientists. Jung's views were entirely similar to those expressed by the subjectivist interpreters of Kant. Using this understanding of Jung's theory of knowledge we can then observe how it was applied by him in two specific cases: 1) Introversion, and the proposed resolution of conflict between inner and outer views through the subjectivized 'esse in anima' are the underlying foci of Jung's theory of types. 2) Jung's study of Paracelsus' doctrine of the 'lumen naturae', of knowledge through inner identity between subject and object, became the springboard for Jung's vast studies of the psychology of alchemistic thought. [...]
The philosophical antecedents of Jung's theory of archetypes are to be found first in Plato's doctrine of transcendent causes, and secondly and more directly in Schopenhauer's dynamic theory of the Will. Nearly all the qualities of Schopenhauer's Will are found reproduced in Jung's theory of archetypes except that, unlike Schopenhauer, Jung insisted that the archetype is directive and form seeking. For this reason he continued to differentiate blindly instinctive from formal, meaning-giving archetypal activity in the psyche, even during the years when the results of experimental studies gave biologists increasing confidence in a phylogenetic source of behavior. In the speculations of his late years Jung extended his theory of non-material, archetypal causes beyond the sphere of individual psychic life to the realm of conjunction with the material world, in his theory of synchronicity.
Jung's theory of individuation and its corollary doctrine of the self can be shown to exactly parallel the classic teleological scheme set out by Aristotle in his doctrine of the Four Causes, operating in a universe sustained by the Unmoved Mover. Aristotle's teleology, expressed in Christian theology as divine intentionality operating throughout creation, became standard doctrine in Western thought until it was challenged in the seventeenth and eighteenth centuries by the development of technical machinery, discoveries in astronomy and physics, and by Kant's challenge to rational theology, and in the nineteenth century by the discovery of the thermodynamic laws and by Darwin's theory of evolution." (Nagy, pp.265-66)
In view of this, it is incorrect to paint Jung as metaphysically neutral. Of course, Jung did not want to be viewed as a religionist or a high-flown philosopher. Arguably, that's why he takes hiding behind the subjectivist credo and says that it's "his own myth". Yet, facts remain that Jung's edifice is firmly rooted in Neoplatonic idealism. Read also my article 'Jung and Swedenborg: modern Neoplatonists':