Sorry about the long delay. The last week has been a little wonky.
Most of what I've come up with is text, actually. There's symbology and visuals that could go along with it, but I haven't thought as much about those. One of my favorite books is Small Gods, by Terry Pratchett. It's about the formation of a monotheism like Christianity, in a world with thousands of gods.
A lot of the quotes are very context-heavy. If you haven't read any of Pratchett's books, they won't make much sense. For example, there's a book, within the book: De Chelonian Mobile: The Turtle Moves. It's a metaphor, within the story, of Galileo Galilei's persecution by the Catholic church.
In the Diskworld books (of which Small Gods is a volume) the world is a huge disk, balanced on the back of 4 giant elephants, which in turn are balanced on the back of a giant sea-turtle, which flies through space.
The Omnians (the metaphorical Catholic church, which worships the god Om) decree that the world is a perfect sphere, in contrast to the reality of the elephants and turtle. De Chelonian Mobile is a scientific text exploring ... basically what amounts to cosmology, in a fantasy world like the one the books are based in.
"De Chelonian Mobile: The Turtle Moves" is one quote I would slip in somewhere. The other major one is a piece of a dialogue between two characters, a member of the Quisition (the Inquisition) of the Omnian church and the ruler of the Ephebian (a metaphor of ancient Greece) people:
"What is it you fear? Here in your desert, with your ... gods? Is it not that, deep in your souls, you know that your gods are as shifting as your sand?"
"Oh, yes. We know that. That's always been a point in their favor. We know about sand. And your god is a rock - and we know about rock."
The polytheism of Ephebe (Greece) represent science. With a substitution of 'science' for 'gods' and a tiny bit of grammar correction (pronouns), that would be perfect. I think Pratchett is an atheist, so I think that's how he intended it, anyway. Of course that would damned near fill my back, by itself. I dunno.
I've tossed around ideas for a back pictorial, myself, so I can cover it up when necessary. I just can't settle on any sort of theme. I'm kind of all over the place. Maybe if i can keep my ideas consistent for more than a month, I'll start putting it together.