How does Dickens explore the theme of poverty through the Crotchet family in A Christmas Carol?

Charles Dickens was one of the most important social commentators of his time. Having a father who was placed in debtors' prison when he was quite young, Dickens had to work in a shoe-blacking house as a boy, and he experienced much deprivation that he never forgot. As a result, Dickens used his literary works to expose social ills and invalidate the idea that the poor were worthless and merely "surplus population."
The portrayal of the Cratchit family in A Christmas Carol demonstrates the love and charity that exists among the family members, as well as their true Christianity. When the Ghost of Christmas Present takes Scrooge to the four-room house of Bob Crachit's, Scrooge is amazed that the spirit would bless such a house. That the family is so excited and cheerful over their meager Christmas dinner also surprises Scrooge, as well as the loving atmosphere of the home. When Scrooge's employee, Bob Cratchit, enters the house, the children run into his arms, and two of the children carry Tiny Tim to the washhouse so that he can listen to the pudding "singing in the copper [pan]." In the meantime, Bob tells his wife that little Tim told him that he hoped the people in church would see him so that they would remember on Christmas Day "who made lame beggars walk and blind men see." 
Tiny Tim sits close to his father, who holds his "withered hand" with paternal care and love as though he wishes to hold him to his side from fear that the boy may be taken from him. Seeing this, Scrooge asks the Ghost if Tiny Tim will live. The Ghost replies, "If these shadows remain unaltered by the Future, the child will die." When Scrooge protests, the Ghost responds with Scrooge's earlier words, saying if the child is going to die, he should do it quickly and "decrease the surplus population." Shamed by his cruel words, Scrooge hangs his head and is "overcome with penitence and grief." Later, as he and the Ghost depart, Scrooge realizes how happy the family is despite their poverty because they are rich in love.