I might posit that, in an infinite multiverse, the gods (yes, all of them) not only could exist but must exist — at least in potential. As with Schrodinger’s famous cat, they both live and do not live for those in our universe until someone actually observes them. This is the basic premise underlying much of my fantasy writing.
It is also a concept used by Roger Zelazny in his ‘Amber’ novels. He questions whether those other universes preexist or are created by the powerful god-like Amberites as they move among them. I admit to the influence, as well as that of Michael Moorcock and undoubtedly others. One thing both Moorcock and Zelazny do, however, is place those realities they created between the poles of ‘order’ and of ‘chaos.’ That is a concept that certainly arises from the whole Indo-European polytheistic tradition — the gods came to create order from the chaos.
That is not a concept I buy into, neither as a author nor as an individual. Nor do I go for the ‘good versus evil’ of the Abrahamic religions. Not that chaos and order, good and evil, do not exist, but they reflect a deeper duality, that of being and nonexistence. One and zero, if you will. I have mentioned this elsewhere, in writing of my personal beliefs, of equating ‘God’ with infinite being. That lies behind my stories, undoubtedly, but I don’t delve into it (not yet, anyway!).
So, the characters in my fantasy novels* do exist in those other realities and some have the ability to cross their boundaries, to varying degrees. Gods, demons, wizards, etc. — all their ‘magic’ is based more or less on these abilities. A god might traverse worlds at will; a powerful human (or other sentient creature) might be able to ‘reach’ into those worlds to find objects or to communicate from afar. It’s almost a scientific explanation, though I take care not to explain it too thoroughly. Leave that sort of thing to the sci-fi people! It just needs to be reasonably plausible without a lot of details.
My upcoming novel, THE CROCODILE’S SON (coming June 3 from Arachis Press!) takes me further afield than my previous books, actually spending time in the world of a family of gods. These are loosely based on Melanesian models — in an infiverse, of course, there would be infinite variations on any pantheon, so I am allowed to shape the characters as I wish. But I must be consistent within any world I do create.
That is why all of the fantasy novels so far are set in the same world, although at various times, with only brief forays into other realities. This is not to say I have not written fantasy stuff that does not fit that world — short stories only, however. One might argue that they, too, exist somewhere in that infinite multiverse, if one likes to argue.
But there is nothing to argue about. They are just stories, after all!
*It might be posited that all fictional characters ‘exist’ in other universes. Are authors, then, creators or are they discovering those worlds? :)