The notion of "appropriate" segregation is present in the First Purchase Chuch just as it is in Maycomb at large. This notion, however, is overcome by a greater sense of community that accepts the Finch children into the church for the day.
Additionally, a sense that there is quite a bit that one side of town does not know about the other. Scout and Jem, for instance, are amazed when the man who collects their trash leads the congregation in song. Zeebo, their garbage, man can sing.
When the children's presence in the church is questioned, we can see the challenge as a reciprocation for negative treatment that African Americans receive in Maycomb. This rather bitter note is important and powerful, yet it is not the sentiment of the entire congregation.
Calpurnia and the pastor both articulate the congregations feelings about accepting the children into the church.
Although the majority of parishioners welcome them during their church visit, one woman challenges the white children. Calpurnia responds by calling them her guests and saying "it's the same God, ain't it?"
One result of the children's visit to the First Purchase Church is a growing awareness that other people have different lives in Maycomb. Even someone close to them, like Calpurnia, has a life of her own that they know little about.
They begin to regard her as a fine friend and as a real person with a life separate from her life with them.
This realization connects with some of the larger moral themes of the novel. Assumptions are challenged by facts and prejudice is proven, often, to be oriented by false beliefs.
This lesson relates to Tom Robinson's treatment in court, to Boo Radley's reputation, and other elements of life in Maycomb.