We do not know exactly on what date the Lord was born to the virgin Mary. It could have been any season, but we have come to celebrate it in the winter. People have always found some special occasion to celebrate hope and love in the midst of darkness and cold, so it makes sense that we observe Christmas at the darkest time in the northern hemisphere.
The first Christmas took place during a dark and terrible time in human history. We Americans sometimes idealize the Greco-Roman world, because we base many of our ideas of law and justice on classical philosophy. However, real Roman life was horrendous. Herod, for example, was appointed by the Romans and was never punished for his evil; this offers an insight into the kind of world Jesus was born into.
Herod's wickedness only plays a small role in the Christmas story; Christmas is mostly a story of warmth and light, love and truth. Think of how the various characters respond to the their part of the Christmas story. Mary and Joseph faithfully take to heart all that is said to them, and embrace the new little life entrusted to them with love, as their own son. Elizabeth and Zachariah struggle with their part but come to see the light of truth and again rejoice in John the Baptist's birth. The Wise Men and shepherds follow in the night to the place where the Lord is born, seeking the light of hope in the Messiah's advent. Each of them responds freely with faith and love.
We, too, have this opportunity. We have the choice to focus on the dark and cold of winter, or on the warmth and light of Christmas. We can choose to welcome the Christmas season with a renewed spirit. We welcome the love and truth of Christmas by sharing warmth and light with the people around us.