They’ve already convinced themselves that Tom’s guilty and that Atticus should just leave the case alone. Atticus says that they’re certainly entitled to think that, same as Dr. Martin Luther King, Jr. respected his critics opinions. However, he says that, before he can live with other folks, he must first live with himself.
“The one thing that doesn’t abide by majority rule is a person’s conscious.” (Lee 87)
This is perhaps the most powerful statement in the novel. You have a moral obligation to judge yourself before you can judge anyone