Doherty does something different, focusing on what may well be the only work we have from this period in antiquity to use “firmament” in precisely the way that it does. The author of the Ascension of Isaiah uses “firmament” for the divider separating the earth and air from the lowest of the heavens, rather than at the top of the realm of heavenly spheres. As R. H. Charles explains, this results from a viewpoint that is unique to the Ascension of Isaiah, namely a refusal to allow evil forces to enter any of the heavenly realms.
(More in keeping with the cosmology of the time is the Apocalypse of Abraham, which calls each of the spheres a “firmament” and makes clearer what these were in the thinking of ancient peoples.)
There is no reason to object in principle to Doherty’s use of an idiosyncratic work to interpret Paul’s letters. If he were to provide a convincing case, there is no reason in principle that these two authors could not have shared a similar cosmology, however different from that of others of their contemporaries. It is simply the lack of evidence from Paul’s letters that he held to the specific cosmology of the Ascension of Isaiah that is the problem, when it comes to this point.
And even in the Ascension of Isaiah, it is clear that Jesus is born on earth and crucified on earth. When Jesus ascends after the resurrection, he pays a visit to the firmament, having to ascend in order to do so. And so even if Doherty were to make the case for the idiosyncratic cosmological view of Ascension of Isaiah being held also by Paul, there is no straightforward step from there to mythicism. As it is, the only work that clearly depicts such a cosmology also depicts the one who descended through those heavens and past the firmament as having appeared a human being in history.
Doherty makes a forced disjuncture between Paul’s letters and the Gospels written within decades of those letters, arguing that it is illegitimate to read the former in light of the latter. And yet he then takes a work from at earliest the second century and more likely the third, and reads it into Paul. This seems to me to be methodologically problematic, to say the least.
But those of us who actually take questions of history seriously, and try to find out what ancient peoples believed and situate the New Testament writings against the cosmology of their time and place, will continue to find such interpretations at best implausible, and certainly not preferable to those mainstream historical conclusions that do justice to the relevant evidence in more persuasive ways. Because just as those who know something about ancient cosmology find Doherty unpersuasive, so too those who know something about Jewish royal messianism in this period find the notion that a group invented a crucified Davidic messiah from scratch even more ludicrous.
Nonetheless, when one considers two “historical Jesus novelists” – Earl Doherty and Dan Brown – it becomes clear that both believe that they have, in contrast with mainstream scholarship, found “the truth about Jesus.” And they manage to persuade significant numbers of people that they are right, because they turn it into a compelling story. And yet they cannot both be right – a non-existent Jesus is incompatible with a Jesus who lived and married and had offspring whose descendants became kings in France. And so we have here a wonderful opportunity to discuss what the difference is, if indeed there is one, between novel-writing and historical writing, and why the former often proves more persuasive than the latter. Presumably if we can get at this, perhaps the heart of the matter, then we’ll be able to figure out why a mythicist can sincerely believe that he’s proven me wrong…again.