Godhead: Book I of the Aldariad

On Vereld, a dark god rises from the grave to plunge the world into chaos and ruin. Named Redeemers by an autistic savant's prophecy, Anili, Jon, and Orrin soon discover that - apart from an ancient mage and a five year-old girl - they are all that stands between the world's continued existence and its ultimate destruction.
On Earth, a cabal of powerful men have discovered a link to Vereld in secret Nazi archives. Now, they are preparing to take over a whole new world and suck it dry.
But worse is yet to come, as an aeons-old, infinitely dangerous entity struggles to break free of its prison in the darkness beyond the stars.