I also tend to think that humans worship or venerated a god and then the vampires comes in to try and take advantage of it.

It seems to me that corruption is almost inherent to vampires, them being more powerful and having advantages over humans, and so it follows known courses that they would corrupt and use things that normal people hold dear to the vampires' advantage

The name "Baali" used by those specific vampires seem like an utter perversion when looking at the character of Baal in the Baal Cycle.

EDITED: Fixed some weird English