In Brisingr, Eragon appears preoccupied with the religious beliefs shared amongst and kept scared by various groups within Alagaësia. Within the first several chapters of the book Eragon declares himself to be atheist, meaning he does not believe in a god or gods and does not follow one specific theology. He goes on to reiterate this truth about himself several more times throughout the narrative. One of the first times that we catch Eragon reacting to a spiritual entity is when he and Arya are returning to the Varden. The two are camping atop a hill when an orb of light approaches. While Eragon is unfamiliar with this phenomenon and takes a skeptical approach, Arya quickly informs him that these spirits are not human entities or their remains; they are a benevolent race of individuals altogether separate. This sighting opens conversation between the two about their religious beliefs.

Later in this volume Eragon experiences several more encounters with spiritual entities that expand and potentially change his definitions of the illogical phenomenon within his worldview. The first example of this appears while he is underground, exploring Farthen Dûr. He finds himself drawn to a specific room and on his second visit he is ambushed by masked dwarves, representing the clan of Az Sweldn rak Anhûin.