James K.A. Smith puts his finger on something that’s worried me about N.T. Wright in his review of Wright’s latest book. Wright sometimes gives the impression that post-New Testament development of Christian theology was a decline and that it’s possible–or desirable–for us to re-inhabit the thought-world of the 1st century (with the help of some judiciously applied knowledge of second-temple Judaism, of course). While understanding the historical context of Jesus’ life and mission is obviously important, Christians have always “translated” the gospel into different cultural idioms. Arguably this process starts in the NT itself: the theological frameworks of the synoptic gospels, John’s gospel, Paul’s letters, the letter to the Hebrews, and Revelation all have their differences. In the post-NT period, this picks up steam with the translation of the Christian gospel into language and concepts borrowed from Hellenistic philosophy, culminating in the debates at Nicaea and Chalcedon.
It’s possible, I suppose, to see all this as a departure from a pristine, “original” gospel. But to do that, you have to explain how we, as 21st-century Christians, are supposed to embrace the worldview (assuming there’s just one worldview) of the NT without qualification. A more promising approach, in my view, is to acknowledge that the gospel is always undergoing a process of reinterpretation and translation, and that this can be done faithfully. The earliest expressions of the faith–while clearly normative in an important sense–aren’t necessarily adequate for all later generations of Christians. For a different, and more positive, take on this process of reinterpreting the gospel through the centuries, I’d recommend Keith Ward’s book Re-thinking Christianity.
A Thinking Reed 
I don’t see why the position you’re working against and the position you’re working for here are in any way in conflict. As a translator and linguist, I can tell you it’s a proverb for good reason that a translation of a translation is worse than a translation of an original. Tom Wright may not be correct about his interpretation of a first-century worldview (his especially focused on the Synoptics and Paul), but there’s a good reason that a growing swath of NT scholarship has grown to see Patristic Hellenism as a departure. And that is that, since the “New Perspective,” we have been peeling back Christianity to observe the ways that even the NT is Jewish — and then Judean — and then, increasingly, a reflection of plural Judean cultures from the entire region.
It is impossible for us to inhabit the 1st century — but it is both possible and highly desirable for us to recreate it, to the best of our growing knowledge, as a process of modeling the probable contexts of these texts that we have. And surely “the gospel is always undergoing a process of reinterpretation and translation, and … this can be done faithfully.” And surely, just as for the generations of the Fathers themselves, “the earliest expressions of the faith–while clearly normative in an important sense–aren’t necessarily adequate for all later generations of Christians.” But the scriptures, as the earliest normative expressions of the faith that we have, are the originals to which we return in every generation to translate the gospel for our generation. But this means that we must always reinterpret — and re-evaluate — the Fathers in light of the scriptures. If the scriptures alone are not adequate, the Fathers and their increasingly Christian translations into pagan Hellenistic contexts do not necessarily improve matters for a people who have never lived in either context. Every translation is a departure in some direction; proceeding ad fontes and, at least initially, against every other translation is the way that we attempt to depart faithfully from the origin.
I think I agree with everything you say here. My point wasn’t to uphold the Patristic era as the be-all, end-all of authentic Christianity, but to say that those developments may have been legitimate ones in their time and not necessarily a “decline.” I agree of course that the NT documents (as well as the OT) are the touchstones to which we always have to return in relating the Christian message to the contemporary era.