I would think that the message has to do with redemption being possible to change one's life. As each spirit revealed, there was a reason for Scrooge's negative reaction to Christmas and its message of giving. The bitter old man was formed by things that occurred in his past-being left alone at Christmas in a boarding school, the death of his sister, the rejection of his fiance. Christmas Past also reminded him of some of the good times (Fezziwig's party, friendship) he had that had slipped into the recesses of his mind. The negative pushed to the fore especially as a result of his business dealings. When Christmas Future showed him a lonely death with only his negativities being remembered and hinting at the death of Tiny Tim, the spirit reminds him that the future is not predetermined. Upon awakening, Scrooge sets out to redeem himself and hopefully keep Tiny Tim from an early death.