Unconscious Mind and Religion
This is an excellent summay of Jung's perspective on the psychology of religious experience by Jung hmself. The focus of this work is on the unconscious as the source of immediate experience of transpersonal realities.
Jung makes clear that the unconscious is the unknown, and that his working hypothesis is that the unconscious is a part of the mind or psyche, but could be something else entirely. His focus is on observable behavior and inferences about the nature of the unconscious.
He acknowledges that religion functions positively to prevent dangerous upsurges of contents from the unconscious. Also, that such outbreaks of pathological contents from the unconscious is the greatest risk of modern society.