Faith was trust in a thing.
Sorin had faith in the revolution.
The Seventh Doctor had faith in his companions, which was strong enough to repel the Haemovores. He had to break Ace's faith in him by belittling her, as her faith was the only thing keeping Fenric's influence active. (TV: The Curse of Fenric)
Relativists in the study of vampirology argued that Vampires could be repelled by faith, often symbolised by items of religious significance such as a Bible, a cross, a Star of David or a swastika. (PROSE: Predating the Predators)