Hazel Mote's grandfather first appears in the story in Chapter One when Hazel, going to sleep on the berth in the train, imagines he is in a narrow coffin and thinks about death and his various encounters with it in his past life. The first ever coffin that he saw as a child was that of his grandfather, who, the text tells us, was a "waspish" itinerant preacher. He was clearly a man of some strength of will as Hazel as a child thinks that his grandfather would never let anybody shut the lid of the coffin on him. However, the lid is closed and he is buried.
The main impact of the grandfather on Hazel is through his powerful strength of will and purpose that makes him such a force in the novel. His influence outlives his life, as Motes seems to want to do anything but become a preacher. However, thanks to his genes, he resembles a preacher and everybody assumes that he is one. Hazel Mote goes around itinerantly, just like his grandfather, but instead of preaching the gospel, preaches a parody of the Christian message, such as this quote that follows:
I preach there are all kinds of truth, your truth and somebody else's, but behind all of them, there's only one truth and that is that there is no truth... No truth behind all truths is what I and this church preach! Where you come from is gone, where you thought you were going to never was there, and where you are is no good unless you can get away from it. Where is there a place for you to be? No place... In yourself right now is all the place you've got.
There is an irony in this novel. Hazel Motes does everything he can to become the opposite of what his grandfather was, and yet other characters identify him as an itinerant preacher and meet God through him. Even Hazel himself has to yield to the redemption of Christ at the end of the novel.