Martin Hengel is a force to be reckoned with.
There is an established scholarly assumption stretching from Harnack and Bousset at the turn of the century to Hengel's own time (1970's) which drew a sharp distinction between so-called "Jewish" or "Palestinian Christian" tradition and "Hellenistic Christian" tradition. The Jewish Christian theology was rudimentary and its christology was "low." The Easter message was its simple kerygma, and the Lord Jesus was a righteous man and martyr whose life and teachings must be taken seriously. This theology was presumably held by the Twelve in Jerusalem. The Hellenists, on the other hand, philosophized the kerygma and complicated things, introducing notions of "atonement" and adding the forgiveness of sins at the cross as a central teaching along with the Resurrection at Easter. Their christology was "high," and it ended up displacing the simple and "pure" Palestinian theology. This theology was held presumably by Paul and his Greek-speaking followers in the late-first century. The result is that a trajectory was set in Christian history that has led to a great deal of misguided scholarship.
In this slim and controversial work, Hengel systematically dismantles these assumptions and refutes decades of critical continental scholarship.
His starting place is where it usually is: the letters of Paul, which represent the earliest of all Christian writings, 20-25 years after Easter.
His method is also what it usually is: taking survey of analogous ancient reflections from Hellenistic philosophy and history, Latin poetry and polemic, Jewish apocalyptic and pseudopigraphy, and Rabbinic commentary and scholia before approaching the Old and New Testament texts with his traditio-historical analysis.
His conclusions are startling. He finds that the earliest believers held no such beliefs as critical scholars have been putting in their mouths for a century. The idea of "low" Christology being the kerygma of the earliest Christians is a myth! It's not represented by any of the literature. From the earliest days of the church, as we see in the traditional material Paul "passes along" to the Romans, Galatians, and Corinthians, (material that Paul learned from the Christians in Jerusalem or Antioch), the vicarious death of Jesus the Messiah forgives sins. There is a soteriological emphasis from the beginning. This message was shocking because, according to Jewish opinion, the Messiah's death would negate his message and his status. However, the Easter miracle overturns this, and proves that God accepted the sacrifice of His Son and Messiah on behalf of the world.
During his highly condensed yet very rich survey of other analogies to atoning death in ancient literature, Hengel concludes that, though there are many examples of righteous men dying on behalf of others, these deaths are local and heroic. They are examples to be followed, rather than sacrifices that prove to be efficacious for all of humanity. The message of the cross is just familiar enough to be heard by Greeks and Romans, yet just unfamiliar enough to be mocked and rejected.
Hengel's conclusion: "[An] independent unsoteriological interpretation of the death of Jesus and his resurrection cannot be shown to be the earliest tradition" (71). The sources do not show this; they do show, rather, an immensely rich plurality of ways that early believers talked about Jesus Christ's death and resurrection.
Along with "Crucifixion" and "The Son of God," this little book forms Hengel's little trilogy that was to be the first part of a "Theology of the New Testament." Each book is scholarship at its condensed finest.