He was born in Kaysersberg, in Alsace, and brought up in Günsbach in the Münster valley, where he attended the local real gymnasium, learned the organ under Charles Widor in Paris, and studied theology and philosophy at Strasbourg, Paris and Berlin. In 1896 he resolved to live for science and art until he was 30 and then devote his life to serving humanity.
In 1899 he obtained his doctorate on Kant's philosophy of religion, became curate at St Nicholas Church, Strasbourg, in 1902 privat-dozent at the university, and in 1903 principal of the theological college. In 1905 he published his authoritative study, J S Bach, le musicien-pote (1905, Eng trans by Ernest Newman, 1911), followed in 1906 by a notable essay on organ design.
In 1913 he published Geschichte der Leben-Jesu Forschung, (Eng trans The Quest of the Historical Jesus, 1910), which emphasized the role of Jesus Christ as the herald of God's kingdom at hand and reduced the importance of Christ's ethical teaching. It marked a revolution in New Testament criticism. Several studies of St Paul, including Geschichte der Paulinischen Forschung 1911, Eng trans 1912) and Die Mystik des Apostels Paulus (1930, Eng trans The Mysticism of Paul the Apostle, 1931), were intended as companion volumes.
In addition to his internationally recognized work as musicologist, theologian and organist, he began to study medicine (1905), resigned as Principal of the theological college (1906) and, when he had qualified in 1913, went with his new wife to set up a hospital to fight leprosy and sleeping sickness at Lambaréné, a deserted mission station on the Ogowe river in the heart of French Equatorial Africa.
Except for his internment by the French (1917-18) as a German and periodic visits to Europe to raise funds for his mission by giving organ recitals, he made his self-built hospital the centre of his paternalistic service to Africans, in a spirit 'not of benevolence but of atonement'.
His newly discovered ethical principle 'reverence for life' was fully worked out in relation to the defects of European civilization in Verfall und Wiederaufbau der Kultur (1923, Eng trans The Decay and Restoration of Civilization, 1923) and philosophically in Kultur und Ethik (1923, Eng trans 1923). He was Hibbert lecturer at Oxford and London (1934) and Gifford lecturer at Edinburgh (1934-35).
He was awarded the Nobel Peace Prize in 1952. His other works include On the Edge of the Primeval Forest (Eng trans 1922), More from the Primeval Forest (Eng trans 1931), Out of My Life and Thought (1931, postscript 1949), and From My African Notebook (1938).