Given Hess's position that Israelites in this period believed in the existence of other gods (a fact Hess finds reflected in the texts), would it not be more appropriate for Hess to argue that this text reflects an interpretation of the events that assumes the existence of Kemosh? There may still be some snags for him here, given his commitment to inerrancy. Perhaps Hess concedes that Israelites believed in other gods, but Hess himself does not believe that Kemosh truly existed. In this case, the text seems to say that Kemosh accepted Mesha's sacrifice and empowered the Moabites to rout Yahweh's forces. Because Hess does not believe Kemosh existed, this is an unacceptable reading. Or perhaps, alternatively, Hess believes there was an entity that was called Kemosh by the Moabites, but this entity was really a demon. In this case, Hess's problem would be with the picture of a demon defeating Yahweh's forces, after Yahweh had promised them victory.
However, in either of the two above scenarios, another maneuver is possible to make. It could be argued that the text is not saying that Kemosh defeated Yahweh, but rather that the Moabites, who believed in the efficacy of human sacrifice, after seeing their king's son sacrificed to their god, became emboldened on the mistaken view that their god was now empowering them. Their boldness resulted in the routing of the Israelites and their allies, sending them into retreat.
Problematic for this position, of course, as I argued in Human Faces of God on pp. 91-92, is that the word qetsep ("wrath") refers to divine wrath most often by far, and frequently to a divine wrath which comes upon a congregation, group or nation. Further problematic is that the word qetsep does not once refer to the wrath of an army, or to the wrath of a group. Perhaps it might have been used this way, but this is a slender reed, since the biblical usage we have does not support it. Nevertheless, I argued that
to the extent that an actual historical battle is recorded here (its historicity is debated by scholars), this reading is probably valid as a sociological explanation for the dramatic shift in the course of the battle. Not many of us would profess belief in the Moabite deity Kemosh. Accordingly, most of us would assume that a human sacrifice to Kemosh could not be in any way efficacious. Yet the soldiers believed in both Kemosh and in the efficaciousness of the sacrifice, and therefore were emboldened to fight fearlessly, thus turning the tides of the battle. We can accept this as a demythologizing intepretation of the text. (p. 92)
But say Hess wants to argue that this demythologized account is what the narrator intended to affirm about the event. I see nothing preventing Hess from this reading. Of course, I think it would be an untenable reading given the usage of qetsep, as discussed above. The most natural reading is that the wrath of Kemosh came upon Israel in response to his servant Mesha's sacrifice. And given (1) Israel's belief in other gods, and (2) the fact that here they are in Kemosh's territory, this reading is further confirmed. But Hess would no doubt not accept my objections to the "wrath of Moab" reading, so what is preventing him from adopting it?
EDIT: It could be the failed prophecy of Elisha preventing him, but it occurs to me now that the text may in fact claim that the prophecy was essentially fulfilled, and thus I may have been mistaken on this point. Elisha's prophecy reads: "This is only a trifle in the sight of Yahweh, for he will also hand Moab over to you. You shall conquer every fortified city and every choice city; every good tree you shall fell, all springs of water you shall stop up, and every good piece of land you shall ruin with stones" (2 Kings 3:18-19).
Then later, the text says, "The cities they overturned, and on every good piece of land everyone threw a stone, until it was covered; every spring of water they stopped up, and every good tree they felled. Only at Kir-hareseth did the stone walls remain, until the slingers surrounded and attacked it" (2 Kings 3:25-26).
The question is whether the wall was destroyed or not. The conjunction 'ad ("until") in v.26 seems to indicate that it was destroyed, but the next verse says that Mesha sacrificed his son on the wall. If the wall was indeed destroyed, then we should read v. 27 as indicating that Mesha sacrificed his son on the rubble of the wall. If not destroyed, then the prophecy was not technically totally fulfilled, although why quibble over a single city wall.
Nevertheless, the fact remains that the Moabites subsequently routed their enemies after the sacrifice of the son, and since this was not expected according to the prophecy, it might be classed as a failure. Either way, it makes no difference to the interpretation of 3:27, and since I doubt Hess will identify the prophecy as a failure, I see no reason why Hess would be prevented from adopting the demythologized reading, assuming he rejects my argument that qetsep does not refer to the wrath of the Moabites.