why does harper lee the auther include this chapter about the ladies missonary circle in the book? What is she trying to show

I think Harper Lee includes the missionary to inject some verbal irony and hypocrisy into the story. The old ladies bemoan the plight of this tribe while they treat their own black residence with such scorn and contempt. This is the ignorance of racism that is so blatant. Even Scout, a little girl, sees the utter lunacy of these women. These women are just so blind to their environment as well as their faith and their inner soul.