This is the truth of the Cainites’ magic: they do not understand it. Sometime, a very long time ago, they were granted insight into a kind of ritualized magic (and some writings intimate that early Cainites stole such rituals from the vampires themselves), and Cainites still have access to and knowledge of these rites today. They even learn new rites. But they do not understand them, and frankly? They don’t care to.
To be clear, being a zealot of the Cainite Heresy is not about asking questions. It is not about deep understanding. The reality is plain: vampires exist. They are a persistent, septic infection. This menace must be destroyed at any cost, no questions asked. Cainites are encouraged to use whatever weapons are available to them, and the Rites of Denial represent one such weapon. Rites of Denial are just another tool in the arsenal, next to a lead pipe or a rough-hewn stake. Not much to grasp about a stake or a pipe, is there? Not much to grasp about the Rites of Denial, either, at least according to the Cainites.