What is this "Christmas spirit", and how can we harness it?
Sometimes when we talk about "spirit", we are talking about a feeling, an ambiance, an idea. Examples would be "school spirit" or "That's the spirit!" or "the spirit of the law vs. the letter of the law."
But you can also speak of "spirits" as living entities. The original Christmas story is full of this kind of spirit. Start in Luke chapter 1 and count the miracles. Between there and the birth of Jesus, I count eight:
- An angel appears to Zechariah and prophesies to him that his wife, who was too old to conceive a child, will give birth to a son.
- Elizabeth, Zechariah's wife, conceives.
- Zechariah is struck deaf and mute when he disbelieves.
- An angel appears to Mary.
- Mary, though a virgin, conceives a son by the power of the Holy Spirit.
- God communicates to Elizabeth and the baby inside her "leaps" when Mary shows up at her door with the news that she is pregnant.
- The Holy Spirit fills Zechariah and he prophesies after his son is born (and, God keeps his word that Zechariah regains his speech).
- God himself steps into space-time history.
Miracles are supernatural. At times the Bible is explicit, that the Holy Spirit does such-and-such. But other times it just indicates the miracle happened by God's hand. In any case, miracles are supernatural events authored by God; and since God Himself is a spirit, miracles are inherently spiritual.
There's a difference, then, between celebrating the "spirit" of the season and the "Spirit" that caused the season. The Christmas story, which begins in Luke 1 (not Luke 2) is a supernatural story. The (Holy) Spirit was at work then, and the Spirit is at work today.
If God the Holy Spirit wasn't needed for the first Christmas, then He isn't needed today. All we would need to do is combine the right elements - snowfall, trees & lights, winter-themed songs, Hallmark Channel movies - and take a few days off of work and school, and we'd have Christmas. On the other hand, if God's hand was essential for the first Christmas to happen (which is of course the case), then the true "Spirit of Christmas" is nothing less than Him - the Holy Spirit.