All of the protagonists in the novel are misfits and social outcasts surrounded by an impersonal and largely antagonistic rural community, which is represented metonymically through minor or anonymous characters. Joanna Burden and Reverend Hightower are hounded by the people of Jefferson for years, in a failed effort to make them leave town. Byron Bunch, though more accepted in Jefferson, is still viewed as a mystery or simply overlooked. Both Joe Christmas and Lena Grove are orphans, strangers in town, and social outcasts, though the former draws anger and violence from the community, while the latter is looked down upon but receives generous assistance in her travels. According to Cleanth Brooks, this opposition between Joe and Lena is a pastoral reflection of the full spectrum of social alienation in modern society.
There are a variety of parallels with Christian scripture in the novel. The life and death of Joe Christmas is reminiscent of the passion of Christ, Lena and her fatherless child parallel Mary and Christ, and Byron Bunch acts as a Joseph figure. Christian imagery such as the urn, the wheel, and the shadow, can be found throughout.
Light in August has 21 chapters, as does the Gospel of St. John. As Virginia V. James Hlavsa points out, each chapter in Faulkner corresponds to themes in John. For example, echoing John's famous, "In the beginning was the Word, and the Word was with God", is Lena's insistent faith in the "word" of Lucas, who is, after all, the father. John 5, the healing of the lame man by immersion, is echoed by Christmas's repeatedly being immersed in liquids. The teaching in the temple in John 7 is echoed by McEachern's attempts to teach Christmas his catechism. The crucifixion occurs in John 19, the same chapter in which Christmas is slain and castrated. However, the Christian references are dark and disturbing—Lena is obviously not a virgin, Christmas is an enraged murderer—and may be more appropriately viewed as pagan idols mistakenly worshipped as saints.
Race and sex
Faulkner is considered one of the foremost American writers on race in the United States, and his novels, including Light in August, often explore the persistent obsession with blood and race in the South that have carried over from the antebellum era to the 21st century. Christmas has light skin but is viewed as a foreigner by the people he meets, and the children in the orphanage in which he was raised call him "nigger." Because of this, he is fixated on the idea that he has some African American blood, which Faulkner never confirms, and views his parentage as an original sin that has tainted his body and actions since birth. Because of his obsessive struggle with his twin identities, black and white, Christmas lives his life always on the road. The secret of his blackness is one that he abhors as well as cherishes; he often willingly tells white people that he is black in order to see their extreme reactions and becomes violent when one white Northern woman reacts nonchalantly. Though Christmas is guilty of violent crimes, Faulkner emphasizes that he is under the sway of social and psychological forces that are beyond his control and force him to reenact the part of the mythical black murderer and rapist from Southern history.
Christmas exemplifies how existing outside of categorization, being neither black nor white, is perceived as a threat by society that can only be reconciled with violence. He is also perceived as neither male nor female, just as Joanna Burden, whom Faulkner portrays as "masculinized," is also neither male nor female and is rejected by her community. Because of this, an early critic concluded that blackness and women were the "'twin Furies of the Faulknerian deep Southern Waste Land'" and reflected Faulkner's animosity toward life.
However, while women and minorities are both viewed as "subversive" and are restricted by the patriarchal society depicted in the novel, Lena Grove is able to travel safely and be cared for by people who hate and mistrust her, because she plays on the conventional rule that men are responsible for a woman's wellbeing. Thus, she is the only stranger who is not alienated and destroyed by the people of Jefferson, because the community recognizes her as the embodiment of nature and life. This romantic view of women in the novel posits that men have lost their innocent connection to the natural world, while women instinctively possess it.
Class and religion
In Light in August, as in most of the other novels set in Yoknapatawpha County, Faulkner focuses mainly on poor white Southerners, both from the upper and lower classes, who struggle to survive in the ruined post-war economy of the South. The characters in Light in August—who are mostly from the lower classes, with the exception of Reverend Hightower and Joanna Burden—are united by poverty and Puritanical values that cause them to regard an unwed mother like Lena Grove with disdain. Faulkner portrays their Puritanical zeal in a negative light, focusing on its restrictiveness and aggression, which has caused them to become "deformed" in their struggle against nature.