There are different models of reality, each one involves different beliefs and assumptions.
I think you're putting the horse before the cart. Firstly, there are multiple ways to model reality depending on which perspective one is looking at it from. The models are simply crafted ways to try to create a framework for analysis and discussion points. The same person could model the same thing any number of different ways and all of them be equally valid and true from each other perspectives held. It doesn't necessarily have to do with prior beliefs and assumptions, but simply searching to create a language to talk about their thoughts and observations.
The "different beliefs and assumptions" you mention happens largely after the fact, when people learn about these models, or the languages and craft their understandings of reality based upon those created models. They learn reality looks like "this" as they explain things to themselves and others in terms of that model. They then begin to "believe" in that model, and they "assume" that model represents the facts of reality. So in this sense the framework becomes reality to them, and reality is contained and explained by the framework.
However I don't see how they are all metaphor.
Because they are all symbolic. They are all linguistic signs to
translate experiences, be they thoughts, ideas, observations, etc, into mental objects. They are not the raw data itself. They are not the thing itself. We've placed a boundary around them and defined it as that boundary. Giving the word "tree" to an object and pointing it does not mean that "tree" is actually what we call it and subsequently believe it to be. It's simply a word we assign to that particular perspective given to the thing. It is of course not invalid to do this as it has usefulness to be sure, but we start to lose sight of the reality of "tree" as we now quickly glance at it and begin to relate to it as that word-sign. But what we are doing is we take this raw experience and then instantly wrap a linguist boundary around it, and then related to it in those terms. We have subsequently
concretized reality within the boundaries of these terms. We take what is inherently metaphors, and make them
facts.
Your syncretic approach might depend on that assumption, but I don't see it as a valid one.
In no way, shape, or form is what I am talking about a "syncretic" approach. I am not taking the symbol of a DNA molecule and putting it on the altar of a deity and calling it Brahma or Vishnu.
Now, that's
syncretism! What I am doing is stepping above ALL the ways we model and talk about the experience of Reality and understanding that science and religion are both doing the exact same thing using different symbol sets and models of reality, experienced from different perspectives.
The challenge for most is to assume one is right and the other is wrong, rather than recognizing they are multiple ways to translate and interpret the world. In no way am I saying when speaking in a scientific context you should use the word Brahman as a scientific term. But I am saying that when someone speaks in scientific terms, it is not
incompatible with religious terms. After all, it is all speaking of different aspects and interpretations of the same Reality.