Short answers, pulled from the story.
Rudolf Bultmann was a German Lutheran theologian who taught the New Testament at the University of Marburg from 1921 until his retirement in 1951, and is considered a major figure in early 20th-century biblical studies. He lived from the 20th of August 1884 to the 30th of July 1976.
Rudolf Bultmann believed that only the "thatness" of Jesus mattered, meaning that Jesus existed, preached, and died by crucifixion, not the specific "whatness" of events in his life. He held that historical analysis of the New Testament was both futile and unnecessary.
Demythologization is Rudolf Bultmann's approach to interpreting the mythological elements of the New Testament in existential rather than literal terms. He set out the idea in a 1941 lecture called New Testament and Mythology, arguing for replacing supernatural interpretations with temporal and existential categories.
Martin Heidegger, who taught at Marburg for five years, built a close intellectual dialogue with Rudolf Bultmann between 1923 and 1928, and Heidegger's existentialism shaped Bultmann's thinking. Bultmann still insisted his theology was not simply Heideggerian philosophy restated, since the New Testament proclaimed a liberating act of God rather than a doctrine of human nature.
Rudolf Bultmann was critical of Nazism from the outset and spent 1933 to 1941 in conflict with the regime over its control of universities and the Protestant Church. He rejected the Aryan paragraph as "incompatible with the essence of the Christian church" and joined the Confessing Church in opposition to a unified pro-Nazi Reich Church.
Rudolf Bultmann's doctoral students included Hans Jonas, Ernst Käsemann, Günther Bornkamm, Helmut Koester, and Ernst Fuchs. He also taught the philosopher Hannah Arendt.