atheism motivated by hatred for gods

[Angrboda]

Not putting this in a specific theoological context, but my hunch is that the brain uses the same processes and cognitive structures to build an "identity" for a fictional character as they do for a real person. Thus, while at some intellectual level, we know they're not real, to the bulk of our brain circuitry, they are just as real as actual people. That's why we become so attached to the fate of a fictional character, and mourn if they are killed off or whatever, because to the brain, they are just as real as actual persons. This, in part, explains why we spend a lot of our time immersed in the lives of fictional characters and events: sure, our reasoning fore-brain vaguely understands they aren't real, but the rest of the brain where the meat and potatoes of cognition occurs, doesn't really care about that distinction.

So I'd say it's perfectly reasonable to hate a fictional character, because fictional and real persons share the same "hardware," and thus at a fundamental level, they are the same.

Of course, I could be entirely out to lunch with this, seeing as it's based mostly on conjecture...