Harper Lee used her book to attack racism in three ways:
1. The narrative point of view through the eyes of a child created an innocence that readers rarely take with them when reading. We always bring our life experiences to every new situation and read with bias. The structure of this novel brings the reader to almost feel like a child, a time when bias was much less in our lives. Dill's experience with Mr. Gilmer calling Tom boy made him literally sick. In fact, Mr. Raymond says of Dill:
Things haven't caught up with that one's instinct yet. Let him get a little older and he won't get sick and cry. Maybe things'll strike him as being - not quite right, say, but he won't cry, not when he gets a few years on him.
Raymond points out the difference between children and adults. Children still have a sense of humanity whereas some adults have worked so hard to squeeze humanity out of their lives. We see the flaw when we readers look through Dill's experience.
2. Lee uses offensive language sparingly, but enough to make readers think about it. She positions noble characters to speak well of racial conflict, while characters readers want to dislike use offensive language regularly. Mr. Glimer is one such character cited above, but Bob Ewell, who readers grow to hate, says this of Tom:
I seen that black nigger yonder ruttin' on my Mayella!
He is one, if not the only, character who uses that term.
3. Lee characterizes groups to demonstrate the pain of racism. When the kids went to the church and first faced Lula, the experience of racism was turned on the white reader. Readers empathized with Scout and Jem, and then experienced the welcome of the rest of the group. This offered great relief. Mrs. Gates, Scout's 3rd grade teacher was racist and Scout struggled with the hypocrisy because Mrs. Gates had preached about how bad Hitler was for hating Jews. The Missionary Circle used the word darky to talk about their servants. This enrages readers because these women are supposed to be Christians. But we find that they are a bunch of gossips. These groups make readers want to correct their behaviors and yet we can't get into the book to do that. So, the only option is to make those changes in our own neighborhoods and churches.
Her delivery of the flaw and pain of racism makes this book an attack rather than a celebration of racism.