A Dusk of DemonsJohn Christopher
science fiction, young adult
In a future world where civilization has collapsed, fourteen-year-old Ben sets out on a journey to discover his birthright, and meets members of a technologically advanced remnant, who use machines to foster belief in Demons among the people of Ben's homeland.
Christoper Samuel Youd, a.k.a. John Christopher (1922-2012), was a British science fiction author. He is best known for The Tripods trilogy.