In the origianl "Battlestar Galactica", there was a supporting cylon who always tormented Gaius Baltar. His name was "Lucifer". In this new incarnation, from what's been gathered up to episode "Download", we know that there is no chip in Baltar's head, that the 6 he fell in love with had no idea he survived, and that the cylons didn't know that the baby was alive.
When I realized there was an old character on the original BG named "Lucifer", and with the show's religious themes, i started my theory that the 6 who talks to Baltar is really, literally, the devil, or at least a devil or demon. Now, after seeing "Downloaded", and how this 6 tells things about the "Cylon 'God' " that conflict with what other Cylons say, and seeing how "Caprica 6" has a Baltar who isn't really Baltar who talks to her and encourages peace, i'm now abso-frakkin-lutely positive that the 6 who talks to Baltar is indeed the devil.
We've seen that the Cylons, while not human, can be humane, and feel all the emotions humans feel. They're just as messed up and imperfect as we are. I believe, much as radical muslims are misled in their faith, the majority of Cylons have been misled in theirs. And who's doing the misleading? "Lucifer", Baltar's 6.
I'm still not sure if Caprica 6's Baltar was another incarnation of the devil, but from it encouraging peace, i wonder if it may indeed be God, or a good god. Either way, i"m pretty sure about one thing: the humans and the cylons have both been played, and their are more things in heaven and earth horatio, and worse enemies, than each other.