I was responding to a quote about Sithis, and that was not what I was talking about. I was asking about how Sithis would not be a God, despite a great number of people believing he is. I have been told that in the TES world, if people believe something about the gods, then it becomes true after a while, which is why Alduin/Akatosh has a bit of a split personality.
That's a bit hard to say. Sithis isn't really a 'he' or 'it' or anything (though I suppose the lack of pronouns to describe nothing is fair use). For what Sithis is (or rather, what Sithis isn't) the concept is not heavily worshipped as a god. The question as to whether he would become a true god through continual worship should be self evident. Until he starts whispering in people's ears or taking some kind of action, he can't really be said to be a god. In the future? Who knows. The very concept is difficult to imagine. Sithis is nothing and from nothing to as to still be nothing but also to be. Perhaps there will be more development in Skyrim. I think it's an interesting concept.
The Vivec bit was towards earlier discussion, and not really related to your post.
Edit: I'd also like to note that in many of these cases, they are intentionally cryptic and that there isn't really one intended conclusion by the developers. So disagreeing is a perfectly valid opinion on the matter.