A Christmas Carol is intended to educate people on the effects of greed. Dickens wants people to read the book and think about the poor and lonely as real people. We are to follow Scrooge on his journey while taking one along with him.
Dickens had a strong belief in social justice. He spent much of his life writing literature with social themes, but A Christmas Carol is the most dogmatic. In lecturing Scrooge, Dickens lectures us.
When the Ghost of Christmas Present rebukes Scrooge for saying that he will not give money to the poor to decrease the surplus population, he is speaking directly to each of his readers that does not want to help the less fortunate.
Will you decide what men shall live, what men shall die? It may be that in the sight of Heaven, you are more worthless and less fit to live than millions like this poor man's child. Oh God! (ch 4, p. 34)
As Marley’s ghost lectures us, Dickens believed that it was each person’s purpose in life to help others.
“It is required of every man …that the spirit within him should walk abroad among his fellowmen, and travel far and wide…” (ch 1, p. 14)
Dickens wants people to realize that the poor, and what happens to them, is everyone’s problem. When the Ghost of Christmas Present shows Scrooge two wretched children, he wants to know who they belong to. They belong to all of us.
This boy is Ignorance. This girl is Want. Beware them both, and all of their degree; but most of all beware this boy, for on his brow I see that written which is Doom, unless the writing be erased. (ch 3, p. 40)
The point is that the poor boys and girls grow up into the ignorant and criminals. They may not be our problem now, but they will be.
Scrooge apparently learns the lesson. As he walks with the Ghost of Christmas Yet to Come, he realizes that any person can change. This is one of Dickens’s most important points. People can change no matter how bad they are, no matter how old they are, and no matter how long they have been the way they are.
“Men's courses will foreshadow certain ends, to which, if persevered in, they must lead,” said Scrooge. “But if the courses be departed from, the ends will change. Say it is thus with what you show me!” (ch 4, p. 50)
With this, Dickens is reminding us through Scrooge that no one is a lost cause. We can all change. That, in the end, is Dickens's lesson for all of us.