He is known for his research on Pietism, secularization, religion and nationalism, transatlantic studies and Martin Luther.
Born on April 29, 1936, in Reutlingen in Baden-Württemberg, he completed his Abitur at the Nargolder Gymnasium in Nagold in 1955 and was an exchange student in Cortland, New York (1952/1953).
Lehmann first studied history, English, German, political science and philosophy at the University of Tübingen and went on to study at the University of Bristol and Vienna and later again at Tübingen.
Lehmann completed his habilitation at the University of Köln under the direction of Adam Wandruszka.
[5] Lehmann also became the managing director and was a member of the Max-Planck-Institute for History in the 1990s.