Now I'd like to flesh out, very, very briefly a few of the details.
(1) The Core Symbols are a key part of the doctrine; they are not merely the vehicles for conveying what is taught, they are such vehicles by themselves being taught (the fact that they are taught rather than merely picked up is part of what explains why one can't give just any old interpretation to them; since they are not merely learned but taught, the way they are taught sets constraints, breakable but real, on what can be learned from them). They are the bulk of the actual teaching. The Propositional and Pragmatic Cores, while they are often (but not always -- it depends on how crucially important people think the doctrine) explicitly taught through proposition and command, are nonetheless vague (which, of course, is different from saying they are unclear); it is the Symbolic Core that fleshes them out and makes them more usable for thought and action. If, for instance, someone says to you: "Worship God," that doesn't get you very far. If, however, you are raised in a community full of rituals, and the command to worship God is put forward in the context of some of these rituals, then you know what to do. If someone says: "Sins will be punished," and leaves it at that, you don't get much out of it. If they say, "Sins will be punished with everlasting torment in the fires of hell, where there is weeping and gnashing of teeth; that is the second death which originally was reserved for the devil and his angels" -- well, that gives you a bit more to contemplate, by bringing in all sorts of different images that can be considered from different perspectives. The symbols themselves may be taken more or less literally; what makes them symbols is not that they are figurative (although they often are), but that they have a point beyond themselves. When people insist that at the end of ages the servants of the Dragon will be chained in everlasting darkness, even if they take it in strict literalness, they generally aren't making an idle observation that they consider irrelevant to anything else. There is a point, even if only an implicit one; and that's what the Propositional and Pragmatic Cores are. But these Cores themselves are often taught by way of the Core Symbols that they organize.
(2) Given that the Propositional and Pragmatic Cores only involve the constitutive and regulative principles involved in the teaching of the Core Symbols, this leaves a lot in play; the Core Symbols are often much richer and more detailed than the Propositional and Pragmatic Cores. Interpretation of them is constrained by these more abstract cores, in the same way that interpretation of anything taught is constrained by the point of teaching it in the first place. But given that the more abstract Cores are vaguely defined this leaves open a lot of room for play of thought. So within the constraints of their context, Core Symbols have a life of their own in actual teaching. They can be evocative and suggestive of things beyond what is conveyed in the Propositional and Pragmatic Cores.
(3) Core Symbols, precisely because they are symbols, may be materially false, in the strict sense (that judged materially they would be formally false). Like anything materially false, however, they can be formally true. An analogy can be to a diagram or a map. Suppose I draw you a map of Little Italy. You can take that map to be more or less accurate, more or less precise, and more or less useful. Unless I've actually misdrawn the map for your purposes (e.g., put Spadina west of Bathurst when the reverse is true and important to your getting to the destination), it doesn't matter how precise or even how accurate the map is; it just needs to be accurate enough and precise enough to meet its purpose. Likewise with the Core Symbols; they can be taken strictly literally or very figuratively without any real difference, so long as interpreting them this way still conforms to the original point of teaching them in the first place. (This point is strictly true of any given doctrine considered on its own. However, given that doctrines can be subordinate to other doctrines the picture can get considerably more complex. For instance, it is simply irrelevant to the doctrine of hell whether one takes the Core Symbols to be strictly accurate. It might not be irrelevant to one's doctrine of revelation.)
(4) Note, by the way, that this doesn't mean that a Core Symbol can't be confirmed or disconfirmed; a map has no truth value, but its accuracy, precision, and utility can be confirmed or disconfirmed. A map might be found to be confirmed in its accuracy but not its precision or utility by new information; or to be confirmed in its precision but not its accuracy or utility by analyzing it; or to be confirmed in its utility but not its accuracy or precision by simply acting on it and seeing where it gets you. So with the Core Symbols. It would be a huge mistake to think that maps can't be confirmed or disconfirmed merely because they have no propositional truth value. (There is actually a parallel to this in philosophy of science; Pierre Duhem argued that theories in physics are not true, i.e., they have no truth value, but that they do admit of confirmation and disconfirmation because they are approximate. The reason he thought this was that he had argued that theories in physics are really classifications. Classifications, like maps and diagrams, have no truth value, but they can be more or less adequate to reality.)
I want to get to Atran, but I'll save that for the next post.