Kaufmann was raised a Lutheran. At age 11, finding that he believed neither in the Trinity nor in the divinity of Jesus, he converted to Judaism."After my conversion, we went to the synagogue together for many years ... ." Kaufmann, W., 1961. The Faith Of A Heretic. Doubleday & Co., p.18. Kaufmann subsequently discovered that his grandparents were all Jewish. Kaufmann left Germany and immigrated to America in 1939 and began studying at Williams College, where he majored in philosophy and took many religion classes. Although he had the opportunity to move immediately into his graduate studies in philosophy, and despite advice not to do so by his professors, he ultimately joined the war effort against the Nazis by serving in U.S. intelligence. During World War II, he fought in the European front for 15 months. After the war, he completed a PhD in the philosophy of religion at Harvard in a mere two years. His dissertation was titled "Nietzsche's Theory of Values" and eventually became a chapter in his (1950).
He spent his entire career thereafter, from 1947 to 1980, teaching philosophy at Princeton University, where his students included the Nietzsche scholars Frithjof Bergmann, Richard Schacht, Alexander Nehamas, and Ivan Soll.