Religion is probably the most notable topic of exploration in A Death in the Family. It is the greatest cause of discussion and strife within both the nuclear family of Mary, Jay, Rufus, and little Catherine, and in Mary's extended family. Mary and Hannah are the only two out of all of the family members who deeply believe in God and the Catholic church.
Near the beginning of the story, Mary prays for her religion not to come between her and Jay; it is obviously something that husband and wife feel different about and disagree about. Mary greatly desires to raise her children as Catholic children, but Jay and the rest of Mary's family do not see the point in such action. However, it seems that Jay and Mary have a relationship that is stable enough to endure their differing ideologies. Early on in the story, when Rufus tirelessly questions Mary about death, she answers solely using religious ideology. We see not only that it will be difficult for her to raise her children without them questioning her beliefs, but also that it will be difficult for Rufus to accept such beliefs because they do not logically make sense.
In Part Two of A Death in the Family, we can see how opposed the rest of Mary's family is to her religious beliefs. The two characters who appear most upset are her brother, Andrew, and her father, Joel. They become visibly angry whenever Mary leaves to pray or beseeches God in their presence to forgive her for grieving. The men's anger stems from their opinion that Mary is wasting her passion and intelligence on religious devotion. Nonetheless, they try to remember fact that she derives some comfort from religion, even if it is hard for them to understand or appreciate.
In Part Three, religion becomes something that is comforting to Mary but that excludes her children. This happens for the first time immediately after Jay's death, when Mary spends most of her time in her bedroom praying. Then, when Father Jackson comes, he cruelly alienates the children and goes into Mary's room with Hannah and shuts the door. Even after the funeral, when the children embrace their mother, they can feel a change in her when she starts to pray, and the feel isolated.
Much of the narrative of A Death in the Family is told from the point of view of children, and primarily through the eyes of Rufus. Agee uses childhood as a lens through which to perceive reality; a child's lack of guile is the best narrative avenue to present many of life's complications, as such presentation allows us to draw our own inferences. Children typify the questioning stance that every character in the novel must eventually embrace when faced with Jay's death.
When we first see Rufus, he is his father's silent companion on a trip to see a Charlie Chaplin film. After the film, we see Rufus's deep love for and insight about his father. The narrator tells us that Rufus perceives that his father loves the silent companionship of their walks home as much as Rufus does, and also that his father needs to spend this time alone, away from the home, because it restores an inner peace he cannot otherwise gain. Rufus clearly adores his father and wishes he could make his father prouder by being a better fighter instead of being good at reading. These two differing feelings—the desire to please and the insight about his father's emotions—are characteristic of Agee's depiction of childhood throughout the novel: at times, Rufus seems very young; at other times, wise beyond his years.