In Chapter 12 Jem thinks that some members of the congregation at the First Purchase African Methodist Episcopalian church do not want the children there because of the remarks that Lula makes to Calpurnia.
Ironically, when the children first arrive at the church with their housekeeper, Calpurnia, the men step back as they remove their hats, and the women fold their arms before their waists. These are gestures of respect and attention to white people. As they move, too, the members of the church separate in order to create a path to the church door.
Just then, Calpurnia is addressed by Lula, who seems seven feet tall to Scout: "What you up to, Miss Cal!" Suddenly, the children are brought to a stop by the pressure of Calpurnia's hands upon their shoulders. In a tone and dialect that the children have never heard before, Calpurnia answers, "What you want, Lula?"
"I wants to know why you bringin' white chillun' to n****r church." [sic]
This question is what frightens Jem, along with Calpurnia's confrontational manner when she replies, "They's my comp'ny." Jem fears that a strong conflict is forming between the two women and he does not want Scout's and his presence to be the cause of any problem.