What insights do Jem and Scout gain from attending church with Calpurnia?

They gain an understanding of the black community. The church they attend is called First Purchase and is a place where worshipers go to on Sunday's and where white men gamble on week days. They realize how difficult it is to be an African American in the south. Or There are many insights Jem and Scout gain. They learn there aren’t many black people who can read. Calpurnia leads a double life of a “white folks’” world and a “black folks’” world. The sermons are almost the same as in their church (expect Rev. Sykes points out specific people). The black people look out for each other as seen when the offering is taken for Helen Robinson. Jem and Scout also learn Helen isn’t able to get a job because of whatever Tom has done.