What explanation does Miss Maudie give for Boo Radley's reclusive behavior?

Miss Maudie says that Boo is still alive, he just doesn't like to come outside. She also says that most of the rumors about him aren't true. Miss Maudie explains that the Radleys are foot-washing Baptists - they believe all pleasure is a sin against God, and stay inside most of the time reading the Bible. She says that Arthur was a nice boy when she used to know him.