The central message of this sermon is that true Christmas celebrations cannot be shallow or superficial, but must acknowledge and confront the darkness and evil in the world. The teacher argues that stories like "A Christmas Carol" and "It's a Wonderful Life" are redemptive because they deal with the dark side of human experience and offer hope and joy in the face of tragedy and pain. This message advances the belief that genuine faith and spirituality must engage with the complexities and difficulties of life, rather than avoiding or trivializing them. The takeaway for listeners is that authentic celebration and joy can only be found by acknowledging and confronting evil, rather than trying to ignore or deny it.