Bauer’s work is helpful for making the point that the labels of “orthodoxy” and “heresy” depend on one’s perspective. The acrobatics that Bauer must perform to make this point are impressive; he must examine several sources for Christianity in the area and determine that many of them have been invented (including the Abgar correspondence, the Doctrina Addai, and 3 Corinthians) or interpolated (sections of the Edessene Chronicle) by later orthodox Christians (the production of Apocrypha is not limited to so-called heretics). If accurate, Bauer shows that orthodox Christians are quite effective at rewriting history to buttress their claim that in all places Christianity began as orthodoxy and was later corrupted by heretics. Though they accede that Bauer is correct about Edessa, conservative writers do not want to accede that Christianity could have developed similarly in other places. Certainly we should be careful not to make arguments from silence, but it is possible that the evidence is simply lost to us. Bauer also illustrates the need to treat orthodox claims about their origins with suspicion; as he states regarding the orthodoxy portrayal of Christian history: “I do not mean to say that this point of view must be false, but neither can I regard it as self-evident, or even as demonstrated and clearly established” (p. xxiv).
1. I'm most curious as to what Tony means by "conservative" and who counts as a conservative (Craig Evans, Ben Witherington?) and what makes them "conservative" (e.g. belief that Scripture is inspired?). I suspect that what Tony means by "conservative writers" is someone who believes the official version of church history given by Eusebius and Luke. While someone who is conservative might be inclined to disagree with Bauer (and Koester, Robinson, Ehrman, etc), nonetheless, and mark this well, disagreeing with Bauer does not make one conservative. I sometimes suspect that Bauer is orthodoxy for the unorthodox and if one disagrees with him one can be (deviant) labelled as a "conservative". Alas the door of ideological orthodoxy swings both ways.
2. The reason why "conservative writers" and others accede to Bauer on Edessa is because he might actually be correct! But this recognition is not a concession granted so that they can say that on the one hand that they take Bauer seriously and then on the other hand deny Bauer's conclusions about orthodoxy and heresy in other regions because it threatens their conservative views. The reason why "conservative writers" and other disagree with his depiction of Christianity in Egypt and Asia Minor is not necessarily because they are conservative, but because they honestly believe that Bauer might actually be wrong!
This characterization of the historical process differs from a view preferred by some scholars. In this other, somewhat romanticized picture, the dominance of "orthodoxy" is asserted to have been only a later and coercive imposition of one version of early Christianity that subverted an earlier and more innocent diversity. Indeed, what became orthodoxy is alleged to have been initially a minority or secondary version in most of the major geographical areas of Christianity's early success. Those who take this view today often cite as the scholarly basis Walter Bauer's 1934 book, Orthodoxy and Heresy in Earliest Christianity, which unquestionably has had great influence, especially since its English translation in 1971. Over the years, however, important studies have rather consistently found Bauer's thesis seriously incorrect. In particular, Thomas Robinson's detailed analysis of earliest Christianity in Asia Minor, and studies of Alexandrian Christianity by James McCue and Birger Pearson as well, concur that forms of Christianity that became designated "heretical" seem to have emerged characteristically in settings where prior versions of Christianity represented emergent proto-orthodox faith and practice. Moreover, Bauer's claim that the second-century Roman church was able to impose its own forms of belief and order translocally is not borne out. In fact, about all that remains unrefuted of Bauer's argument is the observation, and a rather banal one at that, that earliest Christianity was characterized by diversity, including serious differences of belief. Those who laud Bauer's book, however, obviously prefer to proceed as if much more of his thesis is unstainable. Unfortunately, for this preference, Bauer's claims have not stood well the test of time and critical examination. There was, after all, no real means of "top-down" coercive success for any version of Christianity over others until after Constantine, when imperial endorsement and power could be brought to bear. Second-century bishops were elected by Christians of the locale in which they were to serve. So, for example, if a bishop did not have (or could not win) sufficient support from the local Christians, he could hardly impose on them some version of faith contrary to the preferences of the majority. Thus, if any version of Christianity enjoyed success and became more prominent than others in the first three centuries (wehther locally or translocally), it was largely the result of its superior ability to commend itself to sufficient numbers of adherents and supporters. To reiterate the point, the apparent success of what I am calling "proto-orthodox" Christianity was probably the result of teaching and behavior that were more readily comprehended and embraced by larger numbers of ordinary Christians of the time than were the alternatives (pp. 552-53 - I think).
See further: I. Howard Marshall, "Orthodoxy and Heresy in Earlier Christianity," Themelios 2.1 (1976): 5-14