It kind of makes sense.
The problem for me (it may not be a problem for others) arises when the player, knowing that there are NO gods, is asked to play a character who believes that there are gods.
For me, it would be fine for the rules to say, “There will never be any evidence that the gods exist, and there will never be any evidence that the gods don’t exist. Whether or not they exist cannot be known in this game.” THAT would really highlight the conflict in belief: it’s not about figuring out whether or not the gods exist, it’s about struggling with the uncertainty.
If the player knows that the gods don’t exist, then it’s very different from playing, to use your example, “a person that believes might-makes-right.” Might MIGHT make right. We don’t know–there’s uncertainty in this belief! I personally don’t think that might makes right, but that doesn’t make me right. I love that uncertainty, and want to preserve it for the Priest as much as possible.
Faith (in this game) is about the belief of a person in the fact that their actions and choices can be justified by something external.
If the player knows that there is no external justification for their actions, then the game becomes the act of playing a character you know is flawed or wrong fundamentally. I know some players who enjoy playing games like this (for instance, friends who love the game Fiasco). The conflict of the Priest is really enticing for me, but I would not enjoy playing it if I was certain that the conflict was most properly resolved in one direction–I want to be uncertain whether or not the gods are real.
Also:
The World needs to know that there are no gods, because there are none.
Why does this need to be the case? It seems really weird to me that one of the core Fantasy World truths is “Gods are silent” when the truth is that “There are no gods.” If “Gods are silent,” it implies that there are or may be gods, or maybe there were gods once but they all went away (as in, say, Tolkien’s Middle Earth). The gods are still silent in Middle Earth, and all evidence that they were ever here may be gone (beyond old myths and stories), but, in that world, they exist (or existed) all the same.
I don’t know. Do any of these concerns make sense?