"The Grapes of Wrath", Chapters 13 and 14

Throughout the novel, Casy frequently must perform the duties of a preacher. Despite his conviction that he no longer believes in preaching, he is forced into performing the role, whether praying for Grampa as he suffers his stroke or saying a few parting words after his burial. This seems to indicate that Casy is best suited for the role of a preacher, despite his disenchantment with religion. In his parting words for Grampa Joad, Casy does reiterate his belief that people are the source of holiness.