He also wrote a 1965 book on Georg Wilhelm Friedrich Hegel and published a translation of Goethe's Faust, and Martin Buber's I and Thou.

[2][4] Stanley Corngold records that there he "abandoned his commitment to Jewish ritual while developing a deeply critical attitude toward all established religions.

[5][3] His students over the years included Nietzsche scholars Frithjof Bergmann,[6] Richard Schacht,[7] Ivan Soll[8] and Alexander Nehamas.

[2][3] In a 1959 article in Harper's Magazine, he summarily rejected all religious values and practice, especially the liberal Protestantism of continental Europe that began with Schleiermacher and culminated in the writings of Paul Tillich and Rudolf Bultmann.

He forcefully criticized the fashionable liberal Protestantism of the 20th century as filled with contradictions and evasions, preferring the austerity of the book of Job and the Jewish existentialism of Martin Buber.

[10] Kaufmann wrote: "Nobody before Kierkegaard had seen so clearly that the freedom to make a fateful decision that may change our character and future breeds anxiety.

[13] Kaufmann is renowned for his translations and exegesis of Nietzsche, whom he saw as gravely misunderstood by English speakers, as a major early existentialist, and as an unwitting precursor, in some respects, to Anglo-American analytic philosophy.

"[18] Regarding style, Kaufmann argued that Nietzsche's Thus Spoke Zarathustra, for example, is in parts badly written, melodramatic, or verbose, yet concluded that the book "is not only a mine of ideas, but also a major work of literature and a personal triumph.

In the former work he advocated living in accordance with what he proposed as the four cardinal virtues: "humbition" (a fusion of humility and ambition), love, courage, and honesty.