In the Grapes of Wrath how has the Joad family and all the people in general lost their way spiritually?I've already narrowed what I think to...

Lack of unity is another way to look at this novel with regards to the changing the Joads undergo.

At the beginning of their journey, Ma Joad was adamant that the family should stick together. Her outlook was family first before all else. She valiantly attempts to hold the family together, but life on the road proved too much for them.

The deaths of Granma and Grampa Joad due to the stress of the travelling conditions starts the family's unravelling.  Noah does not wish to continue either, and just stays put, never to be seen again. Connie buckles under the strain and leaves his pregnant wife to fend for herself. Ma Joad's vision of family unity disintegrates.

In the end, Tom finds he has to leave his family, as well. He found his calling as a voice for the migrants. Ironically, Al had always wanted to go off on his own, yet stays loyal to his mother's wishes.

While Ma's vision of family unity does not stay together, she finds a unity in the plight of all the migrants. The "poor folks" form their own type of family. They do this of necessity, as they are all finding that families are splitting  apart due to the conditions they are faced with.

Ma learns she is duty bound to care for more than just family. Tom, who previously shied away from personal interaction outside the family, becomes a leader, and Rose of Sharon gives life , not to her own baby, but to a stranger-with her unused milk. The Joads find connections apart from family.