The book frequently satirizes white enslavers' hypocritical version of Christianity. In Chapter 12, after Nat Turner's Rebellion, Jacobs describes how the Black church is demolished and enslaved people made to attend white churches:
The slaves begged the privilege of again meeting at their little church in the woods, with their burying ground around it. […] Their request was denied, and the church was demolished. They were permitted to attend the white churches […]. There, when every body else had partaken of the communion, and the benediction had been pronounced, the minister said, “Come down, now, my colored friends.” They obeyed the summons, and partook of the bread and wine, in commemoration of the meek and lowly Jesus, who said, “God is your Father, and all ye are brethren.”
Jacobs often uses bits of scripture to satirize hypocritical white Christians, and this example is no exception. The white Christians don't seem to grasp the message of their own faith. They say "God is your Father, and all ye are brethren," but they do not treat Black people as brethren. Putting these words into action would require the white minister to recognize that enslaved people are equal humans who should be treated as such. Instead, the white minister's job in the wake of Nat Turner's Rebellion is to convince enslaved people that God means them to be enslaved. It is deeply ironic that the minister welcomes the enslaved people as "brethren" when white people have just demolished their church. Respecting people's religious freedom is supposed to be a fundamental part of what makes a good friend and neighbor in the United States. Enslavers do not want enslaved people to have religious freedom because Nat Turner's freedom to interpret Christianity through his own framework allowed him to lead a violent revolt based on the idea that slavery was a biblical apocalypse. Their only defense against a similar event involves misinterpreting scripture—something Jacobs points out because it makes clear that enslavers do not hold a defensible position.
In this and other moments like it, Jacobs exposes enslavers and white Christians more broadly as people who use Christianity as a tool of oppression instead of living by its teachings. Later on, Linda encounters Reverend Durham of the Bethel Church in Philadelphia. He provides a contrast to Reverend Pike and other white Christians the book satirizes. Instead of using religion to hurt people, he uses his position in the church to help people. This contrast drives home the fact that Jacobs does not have a problem with Christianity itself so much as the way it is practiced in much of the South.
In Chapter 13, Jacobs remarks on the situational irony of white Americans sending Christian missionaries abroad when Americans at home are kept "in the dark" about Christianity:
They send the Bible to heathen abroad, and neglect the heathen at home. I am glad that missionaries go out to the dark corners of the earth; but I ask them not to overlook the dark corners at home. Talk to American slaveholders as you talk to savages in Africa. Tell them it is wrong to traffic in men. [...]
Jacobs does not mean that Christianity is entirely foreign to Americans. Instead, she means that the version of Christianity delivered to both white and Black Americans in the South is a false version of the religion. Colonizers traditionally referred to people in colonized countries as "heathens" if they had not learned or accepted the teachings of Christianity. Missionaries supposedly teach Africans how to read the Bible, enabling them to follow Christianity straight from scripture. The irony Jacobs points out is that there are plenty of "heathens" at home. Literacy rates in the pre-Civil War South were extremely low. Enslavers who controlled the majority of the region's wealth thought that reading or writing might lead people (especially Black people, but also poor white people and others who did not benefit from slavery) to organize and rebel against them. Consequently, enslavers tried not to allow too many schools to operate in the South. Many people only knew scripture through the teachings of ministers, many of whom were paid by enslavers or were enslavers themselves. These ministers had an incentive to teach their followers that slavery was God's will.
This passage exposes the logic behind the entire enterprise of Christian proselytizing as a fallacy. If white Christian Americans were truly concerned about spreading the message of the Bible to as many people as possible, they would teach people at home what is actually in the Bible. Underlying this passage is a not-quite-explicit accusation: "Christian" missionary work abroad and at home alike is a scam. The focus of most of this work is on duping people into believing that Christianity justifies the institution of slavery. Through all this, Jacobs is careful not to alienate the reader who considers themself a true Christian. She herself believes in a truer version of Christianity, one that forbids its followers from treating one another as property. Rather than throw out Christianity altogether, she calls on "good" Christian readers to defend their religion by countering its perversion to justify the institution of slavery.
In Chapter 22, Linda makes new Christmas clothes for her children with materials Grandmother sneaks into her garret hiding place. This moment is laden with situational irony that underscores the tragedy of Linda's situation:
I heard Benny ask a little playmate whether Santa Claus brought him any thing. “Yes,” replied the boy; “but Santa Claus ain’t a real man. It’s the children’s mothers that put things into the stockings.” “No, that can’t be,” replied Benny, “for Santa Claus brought Ellen and me these new clothes, and my mother has been gone this long time.”
How I longed to tell him that his mother made those garments, and that many a tear fell on them while she worked!
When Linda overhears Benny insisting to another child that Santa Claus brought the clothes, she feels opposite to how more privileged readers might expect a parent to feel when they hear that their child believes in Santa. Children whose parents teach them that Santa brings presents for Christmas generally only believe in the fiction of Santa until they are old enough to start questioning their parents' truthfulness. Disbelief in Santa is traditionally a sign of growing up. It is a loss of the kind of innocence that makes children trusting to a fault. Linda has done everything she can to protect her children since birth, but there is only so much she can do to protect the innocence of children who are legally enslaved. Benny has never had the luxury of being able to trust all the adults around him. He seems to insist that Santa is real for a different reason than most young children. Linda can't speak to her children or let them know where she is. Benny received new clothes from someone, and it is more plausible to him that the clothes are from Santa than that they are from the mother he believes has disappeared from his life.
There's additional irony in the fact that Linda actually is right there. She just can't communicate with Benny. This irony drives home the way enslavement breaks up families. Linda has to choose between the possibility of freedom (which she hopes to help her children attain one day too) and an ongoing relationship with her children while they are growing up. She chooses one traumatizing experience over another. Even if she had chosen not to go into hiding so that she could remain fully in her children's lives, their family could have been separated anyway at the whim of their enslavers. For enslaved people, the threat of family separation looms even when families do everything they can to stick together.
In Chapter 25, Linda writes a letter to Dr. Flint and has it delivered to him as though it has come from Boston. This trick creates a sense of dramatic irony that Linda relishes:
The fact that Dr. Flint had written to the mayor of Boston convinced me that he believed my letter to be genuine, and of course that he had no suspicion of my being any where in the vicinity. It was a great object to keep up this delusion, for it made me and my friends feel less anxious, and it would be very convenient whenever there was a chance to escape. I resolved, therefore, to continue to write letters from the north from time to time.
Linda, Grandmother, and Uncle Phillip all know that Linda is right under Dr. Flint's nose, but he keeps looking for her fruitlessly in Boston. This situation is good for Linda's safety because it keeps Dr. Flint from suspecting that she is still living nearby, where he could reach her. But on top of its strategic usefulness, the dramatic irony represents an even greater triumph for Linda. Dr. Flint has long robbed her of power. He has abused her, threatened her, and led his wife to treat her as a romantic rival who must be defeated. Dr. Flint is the reason Linda must spend years of her life in a cramped space, powerless even to stretch her legs or speak to her children. In this one little way, Linda reasserts her own power over Dr. Flint. Although Grandmother is worried that she is playing with fire, Linda finds it the height of comedy to hear Dr. Flint describing how sure he is that he will catch her in Boston. She can't do much from her garret, but she can make him look a fool by exploiting knowledge that she has and he does not. By writing this dramatic irony into her memoir, she makes a show of outwitting him that readers can enjoy over and over again.
On the other hand, the irony is also sad. Linda's children don't know where she is, either. She listens to Dr. Flint assure Ellen that she will see her mother soon because he believes that he will be able to track her down in Boston. Ellen is too young to fully understand the implications of Linda being caught. This very reason is why Ellen cannot be told that her mother is actually still there in Grandmother's garret. The young child should be able to take comfort in her mother's actual presence, but the need to keep as many people as possible in the dark about Linda's hiding place means that Ellen actually takes comfort in the idea that her mother will be caught by her enslavers.