Born in Dresden, Rudolph studied Protestant theology, religion, history and Semitic at the universities of Greifswald and Leipzig in the years 1948 to 1953. Subsequently, for six years he was research assistant while he worked in parallel towards doctorates in theology and as well as religious history. In 1961, he received his habilitation in religious history and comparative religion.
During his work at the Universities of Leipzig, Chicago and Marburg and Santa Barbara (University of California), he has acquired an international reputation as an expert in Gnosticism and Manichaeism. He has also occupied himself with Islam and methodological questions in religious studies.
Here his priority was the creation of a religion studies discipline that was independent of theology. Rudolph stresses that religious studies must be rational science and therefore has a duty to subject itself to a methodological atheism. This thesis, which initially was fiercely contested in German religious studies, is now largely a matter of consensus.
- Die Mandäer I - Das Mandäerproblem Vandenhoek 1960
- Die Mandäer II - Der Kult Vandenhoek 1961
- Theogonie, Kosmogonie und Anthropogonie in den mandäischen Schriften Vandenhoeck 1965, ISBN 3-525-53182-6
- Die Gnosis - Wesen und Geschichte einer spätantiken Religion Leipzig 1977, (4th edition. Vandenhoeck 2005), ISBN 978-3-525-52110-6
- Gnosis und Spätantike Religionsgeschichte, (collected essays, Brill 1997) ISBN 90-04-10625-1