The major turning point in the coming-of-age novel To Kill a Mockingbird is the point at which the verdict is read after Atticus has made his sound argument for Tom Robinson's innocence. There is also a second turning point in the plot with the discovery that Boo Radley saved Jem and Scout's lives.
During the Robinson trial, the children are struck by the incongruities of what they have been taught and the realities of what lies in the hearts of men. When, with surety, Jem tells Reverend Sykes, "Don't see how any jury could convict on what we heard, the pastor replies
"Now don't you be so confident, Mr. Jem, I ain't ever seen any jury decide in favor of a colored man over a white man...."
As the minister proves to be correct, this incident effects a major turning point in the lives of the Finch children. They suffer the loss of their innocence, and it is then that they enter into the real, adult world.
Further in this coming-of-age novel, Jem and Scout put aside another childish illusion. This time it is not as serious as their disappointment in the justice system; it is only the casting off of childish imaginings. At the conclusion of the narrative of Scout, she sees Arthur Radley as a real person, who has saved hers and Jem's lives by stopping the nefarious Bob Ewell in his attempt to murder Jem and Scout.
After Heck Tate and Atticus Finch talk, Scout narrates that Arthur stands against a wall in their home. She speaks to him, and later she escorts him to his house. Before she leaves, Scout views her neighborhood from a different angle as she stands on the porch of the Radley house.
It is not possible to point out only one turning point, as the novel is complex and lengthy. To put it another way, there are many turning points. For example, the trial of Tom Robinson is a turning point, the verdict is a turning point, and the protecting of Boo Radley at the end of the book is a turning point. In fact, we can say that each character has a different turning point. In light of this, let me give my opinion about what I think is a central turning point for many of the characters.
Chapter 8 is a major turning point in the novel. The first seven chapters have a playful feel. The children are playing and obsessed with Boo. In Chapter 8, the setting changes. Coldness literally descend on Maycomb. There is also a death and the burning down of Miss Maudie's house. All of this signals that something new is about to happen--the trial of Tom Robinson.
This trial is a turning point for Atticus, as his courage will be challenged. This trial will also be a turning point for Jem and Scout as they enter into the adult world of racism and hatred. This chapter will also be a turning point for Boo, as he comes out of his house and puts a blanket around Scout. So, what we see here is the seed of the flowering of the book.