I am about a fifth of the way through its 1000 or so pages, so it is early days to draw conclusions. But the gist of Douglas' case is that 'Justification theory' (i.e. 'Justification by faith' asserted as the great Pauline doctrine, especially as construed in Reformation and post-Reformation scholarship, and driving forward modern and post-modern evangelicalism) both misreads Paul and is responsible for many reprehensible developments in the life of Christendom (and its vestigial cultures, including Nazi Germany), the Protestant church, and Protestant theology. To say nothing of leading (Protestant) theology up the garden path of Old or New Pauline Perspective.
Campbell reckons (so far on my reading) to get 'beyond' the Old and New Pauline Perspectives, to rid theology of Justification theory (root and branch), and to establish an apocalyptic rereading of Paul, largely based on Romans 5-8 (rather than Romans 1-4, and Galatians), in which the great doctrine of salvation is God's deliverance of us from evil, drawing us through the Spirit into participatory union with Christ.
What I have not yet read is a proposal to reread Romans 1-4 and Galatians in the light of this new reading, thus (as I understand where this is going) rescuing Paul from charges of contradiction.
So far, then, this blockbuster is a bombshell, at least in the field of my own evangelical thinking (though not completely new, as for sometime my understanding of the heart of Christian experience is that we are 'in Christ').
Is it a bombshell in the field of all evangelical theology? Will it be the seminal work of the 21st century reconfiguring evangelical theology away from Lutheran and Calvinist influence to the 'real' Paul?
Will post again.