Pfister studied theology, philosophy and psychology at the University of Zurich and the University of Basel, graduating in 1898 in the philosophical faculty. He then became a pastor, serving in Wald (canton of Zürich) until 1920. He is remembered for his efforts involving the application of psychoanalysis to the science of education, as well as his belief system in a synthesis of psychology and theology.
Pfister was a pioneer of modern Swiss psychology, belonging to a psychoanalytical circle in Zurich that was centered on Eugen Bleuler and Carl Jung. In 1919, he formed the Swiss Society for Psychoanalysis. Although the psychiatrist Emil Oberholzer founded a separate Swiss Medical Society for Psychoanalysis in 1928, Pfister stuck with the group he had started, defending Sigmund Freud's position on lay analysis that Oberholzer's group rejected.
Pfister was an early associate of Freud, maintaining an ongoing correspondence with him from 1909 to 1939 (the year of Freud's death). Pfister believed that theology and psychology were compatible disciplines and advocated the concept of a "Christian Eros". He was especially interested in Freud's concepts of the Oedipus Complex, castration anxiety and infantile sexuality. From a religious standpoint, Pfister advocated a return to what he saw as the original fundamental teachings of Jesus Christ.
- Psychoanalysis & Faith: the Letters of Sigmund Freud & Oskar Pfister (1909-39)
- 1910: Die Frömmigkeit des Grafen Ludwig von Zinzendorf
- 1917: The Psychoanalytic Method; Charles Rockwell Payne (translator)
- 1944: Das Christentum und die Angst: Eine religionspsychologische, historische und religionshygienische Untersuchung
- 1948: Christianity and Fear (translation of Das Christentum und die Angst)
- Paul Roazen, "Introductory Note" to Pfister, "The Illusion of a Future: A Friendly Disagreement with Prof. Sigmund Freud", International Journal of Psycho-Analysis 74 (1993), pp. 557–58.