In Book 1, Nathan Price alludes to the Bible in order to chastise his family for trying to bring too much luggage on the airplane.
Father surveyed our despair as if he’d expected it all along, and left it up to wife and daughters to sort out, suggesting only that we consider the lilies of the field, which have no need of a hand mirror or aspirin tablets. “I reckon the lilies need Bibles, though, and his darn old latrine spade,” Rachel muttered, as her beloved toiletry items got pitched out of the suitcase one by one. Rachel never does grasp scripture all that well.
The Prices are Evangelical Christians, and Nathan is a minister attempting to spread Christianity to Africa. As a result, there are many Biblical allusions and quotations throughout the novel. This specific allusion to the lilies of the field is from Matthew 6:28. Jesus says, as an example of how God will take care of His followers, "Consider the lilies of the field, how they grow; they neither toil nor spin." The lilies do not strive or work, and yet they are better dressed than even a wealthy king.
Nathan's allusion is meant to encourage his family to leave behind their belongings, since God will provide for them. Rachel's response is ironic: she says that the lilies do need the Bibles and spade her father insists on taking. Leah suggests that Rachel misses the point of this verse, but in a way, Rachel is right. Nathan's condescending allusion applies only to his wife and daughters—he does not follow his own advice to leave behind unwieldy belongings.
In Book 1, Ruth May tries to explain her childish understanding of the religious justification for segregation. She does so by alluding to the myth of Ham from the Bible. While she gets some aspects of the segregationist reasoning correct, her childlike dialect and misunderstandings create a sad irony: even children who don't understand what they're saying can perpetrate racism.
Back home in Georgia they have their own school so they won’t be a-strutting into Rachel’s and Leah and Adah’s school. Leah and Adah are the gifted children, but they still have to go to the same school as everybody. But not the colored children. The man in church said they’re different from us and needs ought to keep to their own. Jimmy Crow says that, and he makes the laws. They don’t come in the White Castle restaurant where Mama takes us to get Cokes either, or the Zoo. Their day for the Zoo is Thursday. That’s in the Bible.
Before this moment, Ruth May alludes to the myth of Ham from the Bible, which was a common justification for slavery and Jim Crow laws (legalized racial segregation in the United States). As she explains, some Christians understood dark skin as a curse from God, meted out to punish Ham and his ancestors and to forever mark them as inferior to others. The original story of the curse of Ham appears in Genesis 9:20-27.
The "Jimmy Crow" that Ruth May mentions is not a real person but instead her childish misunderstanding of segregation laws. These laws were not created by a man named Jimmy Crow but were instead called Jim Crow laws because "Jim Crow" was a derogatory and racially charged term for Black Americans. Jim Crow laws, which were introduced after Reconstruction (the period immediately following the Civil War) and remained in place until 1965, forbade Black Americans from white-only spaces and heavily policed their behavior. These laws existed mainly in the American South, and they kept Black people from entering many schools, churches, train cars, restaurants, and stores.
Another justification for Jim Crow laws was that they protected white women, which adds a significance to Ruth May's assertion that Black people have their own schools "so they won't be a-strutting into Rachel's and Leah and Adah's school." Ruth May claims that it's "in the Bible" that Black people can only go to the zoo on Thursday, but the reader knows this cannot be true, which makes Ruth May's claim ironic. It also illustrates that Ruth May believes, as a result of her childhood in the South, that anti-Black racism and segregation are condoned by God or required by Christianity. Christians both advocated for abolition and promoted slavery; some Christians sought to end segregation, while other Christians violently enforced it. Ruth May's understanding of segregation, delivered in her Southern dialect, demonstrates that the kind of Christianity Nathan preaches is often hypocritical and cruel, and perhaps takes for granted that Black people are inferior.
In Book 2, Orleanna describes Nathan's understanding of Christianity with metaphors, similes, and irony that highlight her confusions about his faith:
But Nathan wouldn’t hear my worries. For him, our life was as simple as paying in cash and sticking the receipt in your breast pocket: we had the Lord’s protection, he said, because we came to Africa in His service. Yet we sang in church “Tata Nzolo”! Which means Father in Heaven or Father of Fish Bait depending on just how you sing it, and that pretty well summed up my quandary. I could never work out whether we were to view religion as a life-insurance policy or a life sentence. I can understand a wrathful God who’d just as soon dangle us all from a hook. And I can understand a tender, unprejudiced Jesus. But I could never quite feature the two of them living in the same house. You wind up walking on eggshells, never knowing which Tata Nzolo is home at the moment.
With a simile, Orleanna compares Nathan's naïve faith to keeping receipts. The simple process of paying for something, keeping the receipt, and getting reimbursed for the purchase later by an authority figure makes more sense in the United States than it does in the Congo, where they are no receipts and, it seems, no reimbursements. Unlike Nathan, Orleanna doubts that their lives are inherently safe because they are on a mission to spread Christianity.
There is also irony in double meaning of "Nzolo," since it can either mean something holy or something humorously and unintentionally gross. Orleanna expands this ironic misunderstanding to show the reader her wavering faith in God. She says she understands the Father of Fish Bait, a vengeful God who would metaphorically "just as soon dangle us from a hook." She also understands a kind and conventional Jesus who is Father in Heaven. But she cannot imagine them metaphorically "living in the same house," as in, being part of the same divinity, which is how Protestants understand God and Jesus.
In Book 2, the Prices get to know the schoolteacher Anatole better when he comes to their home for dinner. Rachel is perplexed when Anatole says he "spent some time at the diamond mines down south in Katanga," and her confusion is an example of situational irony. With allusions and her Southern dialect, she describes how Anatole has presented an entirely different idea of diamonds than the one she's used to:
When he spoke of diamonds I naturally thought of Marilyn Monroe in her long gloves and pursey lips whispering “Diamonds Are a Girl’s Best Friend.” My best friend Dee Dee Baker and I have snuck off to see M.M. and Brigitte Bardot both at the matinee (Father would flatout kill me if he knew), so you see I know a thing or two about diamonds. But when I looked at Anatole’s wrinkled brown knuckles and pinkish palms, I pictured hands like those digging diamonds out of the Congo dirt and got to thinking, Gee, does Marilyn Monroe even know where they come from? Just picturing her in her satin gown and a Congolese diamond digger in the same universe gave me the weebie jeebies.
Rachel alludes to American star Marilyn Monroe, who had recently appeared in the musical film Gentlemen Prefer Blondes, in which she sings a jazz song titled "Diamonds Are a Girl's Best Friend." This allusion sets up that Rachel's understanding of the world is heavily influenced by her time spent in the United States. She never considered that diamonds had to be mined until she meets Anatole, and when she learns this reality, she experiences cognitive dissonance. How can Marilyn Monroe's diamonds come from the Congo when the Congo is the opposite of glamor and wealth? Her Southern teenage dialect ("Father would flatout kill me," "Gee," "weebie jeebies") also illustrates her foreignness to the Congo, as well as her naïveté. Rachel's time in the Congo is reshaping everything she thought she understood, including diamonds.
In Book 4, village chief Tata Ndu interrupts one of Nathan's sermons to hold an election on Jesus Christ. In The Poisonwood Bible, democracy and Christianity are both ideologies that Westerners encourage Africans to adopt. By combining them, Tata Ndu undermines Nathan's power and generates situational irony: the two programs seem to have a fundamental incompatibility.
Tata Ndu turned directly to Father and spoke to him in surprisingly careful English, rolling his r’s, placing every syllable like a stone in a hand. “Tata Price, white men have brought us many programs to improve our thinking,” he said. “The program of Jesus and the program of elections. You say these things are good. You cannot say now they are not good.”
By setting up an election for Jesus, Tata Ndu points out the conflict between Christianity and democracy, which are both ideologies brought from more developed Western nations to Africa. A simile compares Ndu's careful pronouncement of his English words to the precise placement of stones. This simile suggests Ndu's words have weight, like rocks, and that he handles them exactly and mindfully. He wants his message completely understood.
When Tata Ndu tells Nathan that "You say these things are good," he speaks both to Nathan as an evangelical, who has insisted that civilized people are Christians with democracies, and to foreigners who hope to "civilize" Africa in general. The election on Jesus generates situational irony because, despite insisting both Christianity and democracy are good, Nathan also insists they cannot be combined in this way. He also can't offer a coherent reason as to why they cannot be combined. Tata Ndu undermines Western imperial ideology by taking its arguments to their logical extreme, a process that leads to the democratic village-wide rejection of Christianity. Tata Ndu works within the Western framework he's been presented, but in doing so, he makes that same framework seem arbitrary and half-baked.
It's worth mentioning that Christianity and democracy have both coexisted and clashed over Western history. A more thoughtful or patient evangelist than Nathan might have been able to explain why voting on Jesus is a bad idea. But what Ndu rejects here is not necessarily democracy or even Christianity. Instead, he rejects Nathan's self-righteousness and conviction that Americans are more intelligent, civilized, and logical than the Congolese villagers.
In Book 5, Rachel and her sisters have grown up and apart. They've taken drastically different paths, and any empathy Rachel has for the Congolese has evaporated now that she lives in the wealthy and white enclaves of Africa. When she flippantly and hyperbolically describes the Republic of Congo, there's dramatic irony in the fact that her perspective is so different from Leah's, whose explanation of the political strife in the Congo was just pages earlier. The following is Rachel's description:
I received quite an education about politics, as an embassy wife. The French Congo and the newly independent Republic of Congo are separated by one mere river and about a million miles of contemporaneous modern thinking. It’s because they tried to go and do it all for themselves over there, and don’t have the temperament.
After Leah's knowledgeable explanation of the difficulties the Congolese faced in running their own government, including the steps world powers like America took to undermine Congolese self-determination, Rachel's claims carry dramatic irony. She says she "received quite an education about politics," but the opposite turns out to be true (or at least her education is heavily biased toward the colonizers' viewpoint). She hyperbolically says there are "about a million miles of contemporaneous modern thinking" separating the French Congo (still controlled by a European country and, she thinks, superior) and the Republic of Congo. She criticizes the Congolese for self-determination and claims they've failed because of their own inherent inability and temperament. Rachel does not know or care that outside forces prevented legitimate democratic rule in Congo.