I found this puzzle extremely difficult but am glad I persevered. Thanks Arcadia!
I felt it was very well judged in that while I was sorely tempted to complain about sparse checking and unclear instructions (how can one fill the grid without having any information about ring 2?), the trail of breadcrumbs never quite went cold, and between the theme and the clues, all was eventually soluble. The clues were as entertaining solved as they had been bitter unsolved. Quite impressive considering the thematic elements.
Two very minor points I would highlight are the unnecessary biblical reference (although without an equivalent, secular, hint, it's not likely I would've solved the puzzle; unlike other commenters I found that PDM early & helpful!) and the cyclical message from extra letters (a complexity which I didn't feel contributed to the theme). Ah - and carrying out the rotation was a little tedious. But that's unavoidable given this concept, I suppose.
Overall an impressive puzzle - hats off!