Unfortunately, iconography’s bailiwick does not extend very far. As soon as we start to interpret the iconography, to say what it ‘means’, we enter the domain of error, or at least of potential error. There is of course a considerable zone of agreement in the interpretation of the monuments (for example, on the intent of the banquet scene, as discussed above), and little likelihood that the consensus of scholars there is completely mistaken. However, this clear zone of agreement soon gives place to thickets where the intent of the iconography is by no means self-evident and the inferences which are hazarded can at best be no more than plausible.
Supplemented by note 19:
Which is not a reason for not making them: in this field warrantable or grounded speculation is not a vice but a necessity.
Beck's field, of course, is broadly Classics and more specifically Mithraism, but his point holds as well here in the land of Dilettante Bible Geeks, and, indeed, pretty well anywhere in the Humanities.
Beck, R The Religion of the Mithras Cult in the Roman Empire, OUP 2006.