The name "Vampire Bible" is a bit of a misnomer. Unlike the Judeo-Christian book, "The Bible", this is not considered a religious text. Like "The Bible", though, the Vampire Bible does contain stories and parables that describe early vampire history.
It is also not a book in and of itself. It's actually a collection of stories found amongst the writings known as The Scriptures of Delphi.
This collection contains a lot of previously unknown stories that shed light on the origins of vampire history. Probably most fascinating is the vampire origin story, that finally explains the original myth of how the first vampire was created.
As my associates keep digging through the papers and find more post-worthy info, I'll keep it updated on the main vampires page, but I wanted to make sure I explained it in case anyone was confused.