How does the impact that the 16th Street Baptist Church bombing church had on people across the United States support the author’s main idea?

After the 16th street Baptist Church bombing, many people were affected. Many were horrified by this event that killed four innocent girls and shook menu. Activists like MLK Jr. spoke up about it and encouraged people to stand up against racism. People called for action to be taken. This supports the authors idea by showing terrible events that had happened to African Americans back then and how much of a problem it was.
Hope this helps (:

Where are the statements, only the paragraph is here