White guilt is not exactly the right answer.
As a Jewish kid, Macon has a unique perspective on his 'whiteness' because he also Jewish, so he understands the principles of mistreatment, given his ethnic background. However, this leads him to overcorrect when the truth was somewhere in the middle. Instead of loving all people, he fetishizing black people and literally harasses white people with a gun. His final solution? A holiday when white people say they're sorry to black people. And meanwhile, the systemic injustice continues unchecked. The real dilemma facing black Americans has been reduced to emotional responses.
Racial reconciliation is being done poorly by the masses.
By showing that by and large, people accept Macon's poorly crafted response to racial inequality, Mansbach reminds the reader that even the reader is under the author's scrutiny. He's saying that most people have gotten it wrong, so we should be skeptical.
Race is taught wrong in schools.
Look at the education system in the novel. Macon is certainly being misinformed by his white, liberal environment, and the urge to fix problems seems to come before the honest, humble process of studying and understand. Very quickly, the bad answer becomes the powerful answer, because people in positions of academic authority are simple doing what will be popular instead of treating race relations with nuance and patience.
Race isn't something you can wish away.
The title of the book is a nod to Macon's foolish attempt to reject his ethnicity and pretend he's not who he is. Macon is simultaneously afflicted by white guilt and by the desire to be the victim instead of the perpetrator. This makes him the worst kind of person, someone who is hurting the situation by trying to help for selfish, identity-driven reasons.
