Remembering the past
In the past, Black communities can find ample evidence as to why the dominant modes of American life don't work for historically disenfranchised classes. When the community turns its attention away from that unfortunate past, they become liable to make mistakes that cost them and their families.
Unity over division
Another fatal flaw in Linden Hills is that the Black community is so easily broken, especially by the selfishness of those who decide to become rich. Those people who try to break away from the rest for personal reasons often find themselves in some level of hell.
Individuality versus community
The crux of the novel is that the Black community is being punished (in Dante's inferno it seems) for their selfish belief in the American Dream, even when their history is so full of examples of how Black people have been disenfranchised from that dream. The challenge is to resist one's individual ambitions to remember the duty one has to their community. What is the value of someone who makes a million dollars and keeps it for themselves? The American Dream is too individualistic in its scope.