Well... that's assuming you take historical films as historical truth.
Naturally it would be foolish to take historical films as historical truth. It was not my intention to insert the quote from "Spartacus" to act as a sort of historical evidence. It was simply there to underscore my point and hopefully add a little credibility to it insofar as if someone else took the time to write a similar idea into their script, clearly I'm not alone in my thinking. I am well aware that the conversation was entirely fictitious.
While it's true that many in Late Imperial Rome took their legends with a generous pinch of salt (Ovid, for example, is at times extremely irreligious about his subjects in Metamorphoses), it's probably fair to say that there was a gradual progression to this point of easy-going disbelief. The Greeks, for example, almost certainly had a much greater faith in their legends than the Romans who later pillaged their beliefs, and, while some authors may have made their own interpretations of the legends (for example, for Aeschylus to equate the Erinyes with the Eumenides in "Eumendies" was, at the time, extremely controvertial), but you can see the same in any religion. After all, new interpretations are the main reason why most of Europe and America aren't Catholic.
I don't really question any of this. It all seems pretty reasonable. It goes without saying that at some point all cultures, both Mediterranean and non-Mediterranean, believed their myths and gods to be true. If they didn't, they wouldn't have them at all. My point was that, for the most part, much later on, by the time these myths were written down in a form loosely similar to how we know them today, their parent cultures or the foreign observing cultures that recorded them had lost a significant amount of faith in them, and that by that time they had largely entered the realm of fiction. I mean, generally you're not going to write a story about a god unless you're no longer afraid that the god will punish you for blasphemy.
-Phil.