How significant and relevant are the symbols are in A Christmas Carol today?
The symbolism brought into A Christmas Carol by the three Spirits is quite as relevant and significant today as it was when the story was written.
The Spirit of Christmas Past takes Scrooge back into his own history, where Scrooge recognizes the simple joys and deep pleasures brought by people and relationships from his youth, and realizes that he has not allowed those same gifts to be given to others in his present life.
He has the power to render us happy or unhappy; to make our service light or burdensome; a pleasure or a toil...I should like to be able to say a word or two to my clerk just now.
In the same manner, the Spirits of Christmas Present and of Christmas Yet to Come show Scrooge scenes illustrating how his actions and attitudes impact himself and those around him.
While the specifics have changed over the years, the basic themes are the same now as when Dickens wrote the story. No one person has the ability to judge the actions and worth of others; all should be involved in caring for and supporting the people surrounding them.
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. O God! to hear the Insect on the leaf pronouncing on the too much life among his hungry brothers in the dust!