Many persuasive and plausible notions have been put forth in this quest; perhaps more than one is correct - there might not be a single center to the text, but a set of them. In any case, Dietrich Bonhoeffer's approach is novel, asserting more about what the core of the Gospel is not, rather than what it is.
He notes that
factually speaking, Christ has given scarcely any ethical prescriptions that were not to be found already with the contemporary Jewish rabbis or in pagan literature.
Bonhoeffer concludes, then, that the primary message of Jesus is not about ethics - not about what we ought to do, or what we should avoid doing.
He goes on to note that, speaking of religious institutions, Christianity is in many ways similar to other religions, and that Jesus made a habit of attacking religion and religious institutions. Religion, seen in this light, is merely a man-made institution and tradition: "Christianity conceals within itself a germ hostile to the church."
He concludes:
Thus the Christian message is basically amoral and irreligious, paradoxical as that may sound.
While ethics and traditional religious institutions may have their uses, or benefit society, they are not the center of Christ's message, or of the Christian vision. Bonhoeffer has eliminated these two candidates, leaving the door open for a more profound center to the Gospel message: it is primarily about a relationship between God and humans, between Jesus and ordinary people. Relationship exceeds merely moral prescriptions, and transcends traditional institutions. It is a meeting of the minds: in this case, a meeting of mortal finite flawed minds with an eternal divine perfect mind. The opportunity to be in relationship with the Creator of the universe - a relationship which is a harmonious uniting of all things, including forgiveness for my transgressions - is the core of the Gospel message.
