The desire to write this story came from an ancient Chinese artwork depicting demons and gods warring with rockets and firearms. It was anachronistic, of course, for a war at the beginning of time.
But I realised that Western depictions of armored angels wielding longswords was just as anachronistic. In the modern era, surely we should depict our angels with Kalashnikovs, our demons with dirty bombs and the Firmament pitted with holes from reckless A-bomb after A-bomb launched by Satan.
Medievel morality plays depicted the Sanhedrin in the mitres of bishops and archbishops. Inuit myths tell of a mermaid who gave a man a gun, a radio and a gramophone. Avoiding anachronism is a modern conceit.