Sorry. It's late and I read yours wrong (missed the not, couldn't figure out how where you would have gotten him saying there were other gods) I do apologize.
No, I don't know which defenition of lust he meant. But since you don't either how do you know he wasn't talking about one of the many definitions that would require a real person to work?
I was referring to the 'to lust after a woman is already to have committed adultery' (paraphrasing) quote, I'm pretty sure it was this thread.
As for the act, not the actors. Technically lust isn't an act and I do think there is a difference because if they're using a definition requiring an actual person they would care because it'd be impossible to lust after a nonexistant one using such a definition.