Blood Cults
Blood cults are an institution that some vampires found in order to have a constant herd. The concept of blood cults dates back to the First City; they seem to have always been around.
A Kindred demonstrates some of his or her powers to mortals or lets them partake in (usually false) mythic knowledge that makes the mortals something like "chosen ones" in their own eyes. The Kindred acts as a god, guru or the like in this, but always functions as a spiritual mentor and gives his blood to the chosen ones. The reasons to do so are as simple as the idea itself.
Blood cults are a convenient method by which a Kindred can attain vitae and gather loyal followers, not to mention the material wealth and possibilities to influence mortal society through servile and trusting mortals.
Some revenant families have started as a blood cult, and numerous gods of antiquity were represented by Cainites in the first cities, such as Mithras or — the most famous — Seth.
The Inquisition and the Masquerade largely put a stop to this line of action — which is not to say that these nights, there are no blood cults. They simply operate clandestinely.
The Camarilla has made it clear that the patronage of a blood cult equals an effort to violate the Masquerade, and it is forbidden to interact with mortals in such a manner.
The Followers of Set and even some Toreador, on the other hand, often gather massive blood cults in order to corrupt their subjects to the service of their Antediluvian.