What is the theme of A Christmas Carol?

Although "A Christmas Carol" is a simple, sentimental story in many ways, it has generated a great deal of literary analysis and interpretation since its publication in 1843. Various critics have found in it a harsh, uncompromising portrait of the Industrial Revolution in England, a condemnation of capitalism, and a cry for social reform. They often write of Dickens’s contempt for arrogance and hypocrisy and contend that he held a cynical view of human nature, citing as evidence several of the narrator’s asides and some of the speeches delivered by the Ghost of Christmas Yet To Come. Despite its happy ending, they see the story essentially as a dark piece of fiction.
There is no argument that Charles Dickens had an unerring eye for human failings. They are illustrated throughout the narrative, and Scrooge is not the only character who suffers from the weaknesses of human nature. His father is revealed as having been a cold, heartless man during Ebenezer’s childhood, and during Scrooge’s visit to the Cratchit home, we see that gentle, loving Mrs. Cratchit cannot forgive Scrooge for his treatment of her husband. Several especially terrible aspects of human nature are illustrated dramatically in Joe’s shop as the thieves sell the property they have stolen from the dead Ebenezer, including the shirt taken from his body before he is buried.
The story's major theme isn't found in politics or in condemnation of human nature, however, for the primary theme in "A Christmas Carol" is the power of human relationships. On one level, the theme seems quite obvious. The miserly Scrooge rejects the love and companionship of others and lives a miserable life; the reformed and redeemed Scrooge embraces his humanity and finds joy in becoming a part of others’ lives. In the visions of Christmas past and Christmas present, those who are happy are those who relate to friends and family. Simple enough.
The heart of Dickens’s theme, however, is less obvious but more convincing, and like much of the story, it involves children—one child in particular. In the first vision of Ebenezer’s life, he is only a boy, consigned to a lonely life at school where he loses himself in books to avoid the pain of being isolated. His only friends are fictional characters who seem as real to him as other human beings. Being deprived of meaningful relationships at an early age, the story suggests, is the force that sets Scrooge on the path that ultimately robs him of most of his life. Seeing himself alone at school, reading his books, the hard-hearted elderly Scrooge is moved to tears. “Poor boy,” he says, revealing for the first time the pain that his money can’t assuage. In beginning Scrooge’s journey with a trip to his boyhood, Dickens is doing more than following the chronology of his protagonist’s life. He is pointing the reader at once to the most important truth in the story.