Christmas, therefore, is the most unsentimental, realistic way of looking at life. It does not say, “Cheer up! If we all pull together we can make the world a better place.” The Bible never counsels indifference to the forces of darkness, only resistance, but it supports no illusions that we can defeat them ourselves. Christianity does not agree with the optimistic thinkers who say, “We can fix things if we try hard enough.” Nor does it agree with the pessimists who see only a dystopian future. The message of Christianity is, instead, “Things really are this bad, and we can’t heal or save ourselves. Things really are this dark—nevertheless, there is hope.” The Christmas message is that “on those living in the land of deep darkness a light has dawned.” Notice that it doesn’t say from the world a light has sprung, but upon the world a light has dawned. It has come from outside. There is light outside of this world, and Jesus has brought that light to save us; indeed, he is the Light (John 8:12).
― Timothy J. Keller, Hidden Christmas