About me: Lilith is a mysterious figure. She tends to speak in riddles and does not seem to share information lightly. Unlike many of her followers, she doesn't consider herself a god among vampires, stating there is no god but God.
Even after the True Death, Lilith feels responsibility for the continued existence of the vampire race. Going so far as to manifest herself through her blood to secure a new savior in her place.
According to the Book of the Vampyr, Lilith was created by God in His own image: a vampire. Adam and Eve were created to sustain her, beginning the natural order of humans existing to service vampires (although this is never confirmed by Lilith or anyone who could verify it). According to the orthodox religious view, Lilith eventually met the sun at the hands of man. This is in fact false, as the creature that killed her was a fae turned vampire.
Lilith turned the fae Macklyn Warlow into a vampire in the year 3.500 BC, as she was 'told by God' that he would save the vampire race. However, Warlow grew to despise her after he attempted to return home four years later (against her advice), and then proceeded to slaughter his entire village, due to his vampiric instincts. He returned to the cave in which she slept, and used his photokinesis to destroy part of the ceiling of the cave, allowing the sun to come through and destroy the progenitor of all vampires.
However, a small amount of her blood remained. Lilith's other progenies gathered her remains in an earthen jar. At some (possibly multiple) point in the intervening centuries, the remains were transferred, eventually winding up in a fine crystal vial.("In the Beginning") The Guardian's original purpose was to guard Lilith's remains; the Chancellors and the Vampire Authority likely arose later as extensions of the ecclesiastical authority the Guardian wielded. At some point, the Book of the Vampyr was composed, and combined with the Guardian and the last of her blood, a religion enshrining Lilith as a dark saint or even a goddess was born.