In what ways does loss of one's ideology, faith or relationships affect people in the book?

When people in this book lose faith, they lose all hope in surviving so what is the real reason to go on? It must be terrible to lose faith in something that you've had such strong faith in your entire life. Elie loses his faith in God which is something he was very passionate about previous to this. The only reason he goes on is for his father and after his father dies he doesn't care what happens to him.