O'Donovan argues that "evangelical" ethics is ethical living in light of the renewed and renewing creation. The created order--the order of creation, the purpose for which it was established--is vindicated in the cross/resurrection of Christ and is given back to God's people. Although the point is not specifically made, it seems O'Donovan is stressing a teleological ethic (although I wouldn't pin him down on such).
He then proceeds to critique historicist ethics, particularly the Marxist form. Following, he argues that a corollary of ethics is epistemology: the Christian's knowledge is in key and in part a *knowledge in Christ.* While not a primary or exhaustive part of knowledge, *experience* is a factor in knowing. For the Christian knowledge often comes in light of suffering and the way of the Cross (my favorite part of the book).
I found his section on "eschatology" most compelling and most underdeveloped. He seems to posit a realized eschatology. This is good. He anticipates on one hand the coming resurrection but also the the powerful in-breaking of the eschaton into the present order (see thesis of book). Some excerpts:
The resurrection of Christ redeems and transforms the created order (56).
The work of the Holy Spirit defines an age--the age in which all times are immediately present to that time, the time of Christ (103)
Some criticisms:
The book left me with questions concerning "what to do?" Having read it, what should be my response? This is probably the fault of the reader, and thus I need to reread it.
I wasn't quite clear of his criitques of natural law. I was interested in a critique of natural law theories, and he gave some, but I couldn't make sense of them (again, my fault and not OO). On the other hand, however, his critique of the Roman Catholic sexual ethic, based on natural law, was quite good.