The unconscious is the only available source of religious experience.
This is certainly not to say that what we call the unconscious is identical with God or is set up in his place. It is simply the medium from which religious experience seems to flow.
As to what the further cause of such experience might be, the answer to this lies beyond the range of human knowledge.
Knowledge of God is a transcendental problem. ~Carl Jung, CW 10, Para 565
Since we cannot imagine—unless we have lost our critical faculties altogether—that mankind today has attained the highest possible degree of consciousness, there must be some potential unconscious psyche left over whose development would result in a further extension and a higher differentiation of consciousness.
No one can say how great or small this “remnant” might be, for we have no means of measuring the possible range of conscious development, let alone the extent of the unconscious. ~Carl Jung, CW 16, Para 387
Gleaming islands, indeed whole continents, can still add themselves to our modern consciousness. ~Carl Jung, CW 8, Para 387
There are many people who are only partially conscious.
Even among absolutely civilized Europeans there is a disproportionately high number of abnormally unconscious individuals who spend a great part of their lives in an unconscious state.
They know what happens to them, but they do not know what they do or say.
They cannot judge of the consequences of their actions.
These are people who are abnormally unconscious, that is, in a primitive state.
What then finally makes them conscious?
If they get a slap in the face, then they become conscious; something really happens, and that makes them conscious.
They meet with something fatal and then they suddenly realize what they are doing. ~Carl Jung, CW 11:6*