Kunkel's output in his life can be seen as follows:
First Period: 1924-1930: Influenced by Adler - moving toward objectivity
Books:
1. Let's be Normal (1928) - Egocentricity vs Objectivity
2. God Helps Those (1931) - Subject and Object
Second Period: 1930-1936: The We-Psychology (more psychological than religious)
Books:
1. Character Growth in Education (1931 in German/ 1938 English translation)
2. What it Means to Grow Up (Early 30's in German / 1936 English translation)
3. Conquer Yourself (Early 30's 1936 English translation)
Third Period 1936-1942/3: Integrating C. Jung
Book:
1. In Search of Maturity (1943)
Fourth Period 1942/3 - 1948: The Religious We-Psychology
Book:
1. Creation Continues (1947)
Kunkel died in 1956. His archive has extensive notes and lectures of what would have become further books. These are conceptulised by Kunkel as follows:
1. Paul - Growing Consciousness, a psychological interpretation of the life and letters of the Apostle Paul.
2. Call of the Future - the Foundation of a Religious Psychology.
3. Man of the Future - the individual finding his own identity through ever-growing relationships with other human beings.
4. Teleo-Pathology* - the dynamics of crisis in the development of individuation. The maturing process of man as seen in psycho-pathological process.
A fifth work was projected about the Gospel of John - with the description: As the psychologist reads the New Testament.
It seems to me that in Kunkel's lifetime, he laid the foundations for a true Religious psychology with his We-Psychology which focuses on understanding and overcoming our egocentric defenses. His projected work was to build on this and flesh out what a 'Religious Psychology' actually constitutes in practice once we have dealt with and reckoned with the content of our unconscious. We are then in a position to respond to the future's call.
*Teleology in psychology refers to the principle that human behaviour is goal oriented and driven by future purposes rather than purely reactive to past causes. This would have been the focus of Kunkel's unwritten work.
I hope to access this material and publish it on this website. It may take some time.