Hengel was born in Reutlingen, south of Stuttgart, in 1926 and grew up in nearby Aalen. In 1943 he was conscripted as a 17 year-old schoolboy into the German Army and served in an anti-aircraft battery on the Western Front. In 1945, after one of the final battles of World War II, he threw away his weapons and uniform and walked home from France, completing his schooling in 1946. In late 1947 Hengel began his theological studies in Tübingen, moving to the University of Heidelberg in 1949. In 1951 he qualified as a Lutheran parish minister, but in 1954 his father voiced his opposition to this and insisted that he join 'Hengella', the family textile business in Aalen, which makes women’s underwear and lingerie.
This caused a ten-year struggle for Hengel, who had to study when he could based around his working hours. The strain on his health led to a serious breakdown. He later referred to these ten years as "wasted years" and gave the impression of almost having an inferiority complex about the amount of study he had been forced to miss. However, he remained a director of the company until his death. In August 1957 he married Marianne Kistler.
For a short period he was also able to lecture at a theological college, and served as an assistant to Professor Otto Michel in Tübingen, but this ended in 1957 when he was sent to manage a factory in Leicester for several years. He continued to work on his doctoral thesis in his spare time. Hengel graduated in 1959 with a PhD. He completed his postgraduate work on his Habilitation thesis, a requirement for academic teaching, at the University of Tübingen in 1967. His thesis was concerned with Judaism and Hellenism. He was a professor at the University of Erlangen starting in 1968. In 1972 Hengel returned to Tübingen to succeed Professor Michel.
In 1992 he was Emeritus Professor of New Testament and Early Judaism at the University of Tübingen. Hengel specialized in the early period of Rabbinic Judaism including early Christianity and the origins of Christianity. He considered the traditional account that the Gospel of Mark was written by Peter's interpreter to be essentially credible.
This period of Judaism includes early Christianity and the field known as Christian Origins. Much scholarly work is currently being done around the intersection of Hellenism, Judaism, Paganism, and Christianity and the ways in which these terms are potentially problematic for the Second-Temple era. Such work of the past two or three decades follows 50 years of work by Hengel, who reconceptualized the scholarly approach to the period in such works as Judentum und Hellenismus, and other scholars.
His Institute for Ancient Judaism and Hellenistic Religion attracted scholars from all over the world, including Israel, and the Philip Melanchthon Foundation, which he founded, brought young scholars close to the world of Greek and Roman antiquity.
He received honorary doctorates from the universities of Uppsala, St Andrews, Cambridge, Durham, Strasbourg and Dublin. He was a corresponding member of the British Academy and the Royal Netherlands Academy of Arts and Sciences.
Hengel died aged 82 in Tübingen, and is survived by his wife, Marianne.
- Judentum und Hellenismus : Studien zu ihrer Begegnung unter Berücksichtigung Palästinas bis zur Mitte des 2 Jh.s v.Chr.. Tübingen: J.C.B. Mohr, 1973
- Judaism and Hellenism : Studies in Their Encounter in Palestine During the Early Hellenistic Period. 1st English ed. 2 vols. London: SCM Press, 1974.
- Crucifixion in the Ancient World and the Folly of the Message of the Cross. Philadelphia, Pa.: Fortress Press, 1977.
- Acts and the History of Earliest Christianity. London, SCM Press, 1979.
- Jews, Greeks, and Barbarians : Aspects of the Hellenization of Judaism in the Pre-Christian Period 1st American ed. Philadelphia, Pa.: Fortress Press, 1980.
- The Charismatic Leader and His Followers. 1st English ed. New York, NY: The Crossroad Publishing Company, 1981.
- The Atonement: The Origins of the Doctrine in the New Testament. Philadelphia, Pa.: Fortress Press, 1981.
- Between Jesus and Paul: Studies in the Earliest History of Christianity. London: SCM Press, 1983.
- The Zealots : Investigations into the Jewish Freedom Movement in the Period from Herod I until 70 A.D. Edinburgh: T. & T. Clark, 1989.
- The 'Hellenization' of Judea in the First Century after Christ. London: SCM Press, 1989.
- The Four Gospels and the One Gospel of Jesus Christ : An Investigation of the Collection and Origin of the Canonical Gospels. 1st North American ed. Harrisburg, Pa.: Trinity Press International, 2000.
- (with Anna Maria Schwemer) Jesus und das Judentum (Geschichte des frühen Christentums, Bd. 1). Tübingen: Mohr Siebeck, 2007.
- Obituary in The Times
- "Theologe Martin Hengel gestorben". Dorstener Zeitung.de. 2009-07-02. Retrieved 2009-07-02.
- Obituary in The Daily Telegraph 13 July 2009
- "Daily Times - Leading News Resource of Pakistan - Ancient Jewish man’s remains give clues on crucifixion". www.dailytimes.com.pk. Retrieved 2008-01-23.
- Theissen, Gerd and Annette Merz. The historical Jesus: a comprehensive guide. Fortress Press. 1998. translated from German (1996 edition). p. 26.