Within a posting in Deane's blog that explains how the birth narratives in Luke and Matthew are irreconcilable, there is an interesting comment:
Yet, despite the dramatic differences, conservative Christian interpreters will attempt--in various ways--to provide a 'harmonization' of the two stories. The means by which they attempt a harmonization usually involves saying that each Gospel nativity story 'omits' some of the details of the 'full and real historical story'. For example, as Luke does not mention a flight to Egypt, conservative interpreters argue that--far from Luke having contradicted Matthew--we should understand Luke as having preferred to narrate other events instead, and to have merely 'omitted' the flight to Egypt. So, the 'full and real historical story' can be reconstructed by 'inserting' the flight to Egypt, along with other bits only mentioned in Matthew, into Luke.I think these two paragraphs highlight very clearly one of the fundamental failures of conservative theology. The desperation to salvage the literal truth of fundamentally different Gospel narratives forces conservatives to concoct scenarios that are not mentioned in either, just in order to link the disparate narratives together. The glue that they use to join these scenarios together is not found in either narrative. Thus we have the irony that those who claim that the Bible alone is the literally true foundation of their theology are forced to rely on invented scenarios in order to bring together those disparate elements. It's an inherently self-contradictory posture. In order to preserve the literal truth of the Bible, one is forced to do what one ostensibly opposes--going outside of what was spelled out in the narrative itself (in this case, by engaging in a process of creative imagining of what must have taken place but what wasn't specified.) We see this same phenomenon, of course, when conservative Christians try to meld together the two creation stories in Genesis.
This strategy may well result in a technically possible harmonization, if carried out with enough ingenuity. But what emerges is a third story, alongside Matthew's and Luke's, that doesn't sound like either Matthew's or Luke's nativity story. Ironically, the effect of such a harmonization--in a case like the nativity stories--is that the conservative Christian interpreter prefers the story he concocted himself to the biblical accounts of both Matthew and Luke. The attempt at harmonization results in significant changes to the particular structure of the narrative and particular themes which Matthew or Luke each intended to convey. It also requires the addition or subtraction of facts so as to force the two accounts to fit together.
These efforts at explaining away the contradictory narratives are akin to the epicycles that astronomers used to explain away the anomalies in the Ptolemaic paradigm.
Not only is the ostensible goal of rescuing the Bible's literal truth dependent on this sort of imaginative glue, but as the blogger points out, these efforts essentially destroy the spirit of each of the individual narratives. In other words, to paraphrase an infamous quote from the Vietnam War, "It was necessary to destroy the Gospel narratives in order to save them."