Neither Atticus nor Alexandra were aware that Jem and Scout had gone with Calpurnia to her church until Scout brought up the question about rape with him. When Scout told her father about their visit to First Purchase Church,
... Atticus seemed to enjoy it, but Aunt Alexandra, who was sitting in a corner quietly sewing, put down her embroidery and stared at us.
Although it was not immediately evident, Alexandra must have thought this was a terrible decision on Cal's part. When Scout suggested that the next Sunday would be a good time for her to visit Cal's house in the Quarters, Alexandra responded,
"You may not."
It prompted an angry response from Scout--"I didn't ask you!"--which brought Atticus to his feet with the demand that she apologize to her aunt. Later that night, Atticus and Alexandra became embroiled in an argument about Cal: Alexandra wanted her fired, but Atticus stood firm, telling his sister that
"... Calpurnia's not leaving this house until she wants to... We still need Cal as much as we ever did...
"--and another thing, the children love her."