Helmut Koester (December 18, 1926 – January 1, 2016) was a German-born American scholar of the New Testament and early Christianity at Harvard Divinity School. His research was primarily in the areas of New Testament interpretation, history of early Christianity, and archaeology of the early Christian period.
Koester was born in Hamburg. He studied under Rudolf Bultmann at the University of Marburg, Germany, after being released from a POW camp there in 1945. He submitted his dissertation in 1954, and then became an assistant to Günther Bornkamm at the University of Heidelberg from 1954-1956. Koester began teaching at Harvard Divinity School in 1958 and became John H. Morison Research Professor of Divinity and Winn Research Professor of Ecclesiastical History in 2000. Koester was co-editor and chair of the New Testament editorial board of the commentary series "Hermeneia: A Critical and Historical Commentary on the Bible" published by Fortress Press (Minneapolis). He served as the president of the Society of Biblical Literature (1991), was member of the Studiorum Novi Testamenti Societas (SNTS) and was elected a Fellow of the American Academy of Arts and Sciences.
Koester was an ordained minister of the Lutheran Church. In 1953, he married Gisela Harrassowitz, with whom he had four children, named Reinhild, Almut, Ulrich, and Heiko. He had three grandchildren including Christopher, Lukas, and Alexander. He died on January 1, 2016 at the age of 89.
In his dissertation (published as Synoptische Überlieferung bei den Apostolischen Vätern, i.e. "Synoptic Tradition in the Apostolic Fathers"), Koester was able to demonstrate that much material in the so-called Apostolic Fathers that parallels elements in the Synoptic Gospels need not necessarily reflect dependence upon the written form of the Synoptics known to us. This was an extremely significant observation, and one with which all subsequent scholarship on early Christian gospel traditions would have to reckon. Among his numerous subsequent publications, his two-volume Introduction to the New Testament has become a standard reference work.
- Synoptische Überlieferung bei den Apostolischen Vätern (TU 65; Berlin 1957)
- with James M. Robinson. Trajectories through Early Christianity. Philadelphia: Fortress, 1971. Reprinted, Eugene, OR: Wipf & Stock, 2006. (ISBN 159752736X)
- Ancient Christian Gospels. Harrisburg: Trinity Press International, 1990. (ISBN 0334024501)
- Introduction to the New Testament: History, Culture, and Religion of the Hellenistic Age, Vol. 1, New York: De Gruyter, 1982. 2nd ed., 1995 (ISBN 3110146924)
- Introduction to the New Testament: History and Literature of Early Christianity, Vol. 2, New York: De Gruyter, 1985. 2nd ed., 2000 (preview).
- Paul & His World: Interpreting the New Testament in its Context Minneapolis: Fortress Press, 2007. (ISBN 0800638905)
- From Jesus to the Gospels: Interpreting the New Testament in its Context. (ISBN 0800620933) Minneapolis: Fortress Press, 2007.
- Pearson, Birger A. et al. (eds.) (1991). The Future of Early Christianity: Essays in Honor of Helmut Koester. Minneapolis: Fortress Press. [ISBN 0800625218]
- Smith, James D., III and Philip Sellew (eds.) (2007). The Fabric of Early Christianity: Reflections in Honor of Helmut Koester by Fifty Years of Harvard Students, Presented on the Occasion of His 80th Birthday. Eugene, OR: Pickwick Publications. [ISBN 9781597529747]