The goal of
Monsignor Pruitt
throughout much of the show was to slowly bring people to a point where they would accept the sacrament of
turning themselves into vampires by dying and being reborn.
However, why did he do this? Just drinking the blood was enough to provide "life everlasting," since as we saw, it restored people to a youthful state and perfect health, without any need to die and become a vampire. One might imagine that Pruitt was aware (from having been told by the winged vampire?) that dying and being "reborn" would provide a more durable form of immortality, since it would provide invulnerability (or substantial resistance) to injury. However, he then certainly must have been aware (or at least have strongly suspected) that it would induce a severe vulnerability to sunlight, which arguably negates that benefit.
Why, then, did Pruitt think that it was necessary for everyone to die and be reborn, instead of simply living indefinitely with a steady supply of vampire blood?