I would think the real giveaway that this is a gag is - what is it running on? No platforms announced, I doubt Nintendo would allow this on the Wii, and most people (myself included) don't have a PC hooked up to the TV.

But yeah this is pretty much Poe's Law in action - I really do have to give it 50/50 that this is real (or at least someone's attempting it).

But biblical games themselves are far from unprecedented.
http://www.gametrailers.com/user-movie/avgn-bible-games-part/139678