John's first two years there passed pleasantly. The fathers of all the boys were money-kings and John spent his summers visiting at fashionable resorts. (1.4)
Notice that the patriarchs are described as "money-kings" – already there is an element of the mythological in this story.
John T. Unger came from a family that had been well known in Hades—a small town on the Mississippi River—for several generations. (1.1)
Notice that Fitzgerald introduces religion in the first sentence of his story – before we've even started talking about wealth or power. This supports the argument that "The Diamond as Big as the Ritz" might be primarily concerned with religion.
When [John] told them where his home was they would ask jovially, "Pretty hot down there?" and John would muster a faint smile and answer, "It certainly is." His response would have been heartier had they not all made this joke—at best varying it with, "Is it hot enough for you down there?" which he hated just as much. (1.4)
There is a double meaning to this question. On the one hand, the men may be referring to the fact that John is from Mississippi – a far cry from Boston and of course a different (much hotter) climate. But it's also yet another poke in the ribs for the reader to remind him that John is from Hades, another name for Hell.
John T. Unger
They were obviously ascending, and within a few minutes the car was crossing a high rise, where they caught a glimpse of a pale moon newly risen in the distance. The car stopped suddenly and several figures took shape out of the dark beside it—these were n****es also. Again the two young men were saluted in the same dimly recognizable dialect; then the n****es set to work and four immense cables dangling from overhead were attached with hooks to the hubs of the great jeweled wheels. At a resounding "Hey-yah!" John felt the car being lifted slowly from the ground— up and up—clear of the tallest rocks on both sides—then higher, until he could see a wavy, moonlit valley stretched out before him in sharp contrast to the quagmire of rocks that they had just left. Only on one side was there still rock—and then suddenly there was no rock beside them or anywhere around. (2.16)
There's something almost ritualistic in the way that Percy and John travel slowly to their destination. There are stations on the way, and certain procedures which must be observed. The process has an air of sacred secrecy about it, like some sort of cult ceremony.
[The prisoners:] "Come on down to Hell!" (6.17)
Again we're faced with the duality of Heaven and Hell. The Washington estate is presented as an Eden, a garden of paradise, and here, below ground (fittingly), the men are in Hell.
He did not know that the little gold football (inscribed with the legend Pro deo et patria et St. Midas) which he had given her rested on a platinum chain next to her bosom. (7.1)
"Pro deo et patria" is a common motto for many schools, and translates from the Latin to "For God and country." The St. Midas motto, of course, has a double meaning: for God and country and the school, but also for God and country and the worship of wealth.
"I didn't," burst out Kismine. "I never invited one. Jasmine did. And they always had a very good time. She'd give them the nicest presents toward the last. I shall probably have visitors too—I'll harden up to it. We can't let such an inevitable thing as death stand in the way of enjoying life while we have it. Think how lonesome it'd be out here if we never had any one. Why, father and mother have sacrificed some of their best friends just as we have." (8.33)
Again, there seems to be something ritualistic about the Washingtons' way of functioning. In this particular passage, Fitzgerald may be poking fun at religion in his justification of seemingly ridiculous behavior.
Above, under the misty moon, sliding in and out of the patches of cloud that eddied below it, floated a dozen dark-winged bodies in a constant circling course. From here and there in the valley flashes of fire leaped toward them, followed by sharp detonations. (9.18)
Notice the religious allusions in this (and other related) passages regarding the attack on the Washington estate. The aeroplanes are described like dark angels, and Fitzgerald might as well as have used the words "fire and brimstone" to describe the ammunition raining down on the chateau.
That, John perceived after a time, was the thread running through his sentences. Prometheus Enriched was calling to witness forgotten sacrifices, forgotten rituals, prayers obsolete before the birth of Christ. For a while his discourse took the form of reminding God of this gift or that which Divinity had deigned to accept from men—great churches if he would rescue cities from the plague, gifts of myrrh and gold, of human lives and beautiful women and captive armies, of children and queens, of beasts of the forest and field, sheep and goats, harvests and cities, whole conquered lands that had been offered up in lust or blood for His appeasal, buying a meed's worth of alleviation from the Divine wrath—and now he, Braddock Washington, Emperor of Diamonds, king and priest of the age of gold, arbiter of splendor and luxury, would offer up a treasure such as princes before him had never dreamed of, offer it up not in suppliance, but in pride. (10.13)
The word choice in this passage brings us back to mythology and ancient history. "Prometheus Enriched" refers to a play by Aeschylus called "Prometheus Bound." This simultaneously refers us to the story's religious and mythological allegory, and brings us back to its satire on wealth.