Some theological ponderings. If this doesn't interest you, feel free to skip this post.
This post involved so much discussion and editing with my husband during the course of its writing, that I have to give him full credit as a co-writer
In recent years, I've heard a number of well-intentioned people referring to Christmas as "Jesus' birthday". Factually, there is nothing wrong with this characterization. We are celebrating His birth, after all. But something about it always bothered me, and I just couldn't put my finger on why. It's a term that people use in an attempt to "take back Christmas" and remind themselves of what the day is really about. I can respect the sentiment. Reflecting on it, though, I realized that this is ultimately a misguided and overly simplified way to explain the meaning of Christmas.
The first time I heard anyone refer to Christmas as "Jesus' birthday" was in the classic movie The Bells of St. Mary's. A group of schoolchildren, after performing an adorable Nativity Play, sing "Happy Birthday" to Jesus (complete with sweet little bowed heads as they speak His name - ah, be still my heart!).
[A clip of this scene used to be on Youtube, but it seems to have been taken down, and I'm really bummed about it.]
I don't have a problem with children referring to Christmas as Jesus' Birthday. Birthdays are something they "get". But the same term sounds rather puerile coming from an adult. Cutesy customs like baking a birthday cake for Jesus and singing Him "Happy Birthday" on Christmas morning might be better than just doing the whole Santa/presents/mistletoe thing while ignoring the real "reason for the season", as they say. But it's still missing the point somewhat. And even when you're dealing with young children, I think you can go a lot further than just teaching them to think of Christmas as someone's birthday, even if that Someone is the Lord Himself.
A birthday is the commemoration of the day someone was born. However, the day a new baby is born into the world is always a "bigger deal" than all his or her subsequent birthdays which merely commemorate that day. From a liturgical perspective, when we celebrate Christmas (or any other feast day, for that matter), we are participating in the reality of that event. As my husband put it, "our Faith is not a commemoration of history, but a living faith." On Christmas we experience the reality of God made Man - it's not merely a memorial. And this isn't just the birth of any child. This child is our Savior - the one we've been waiting for and preparing for for so long. Now that is awesome, in the true sense of the word. On Christmas morning, we can joyfully say, "Christ is here with us! He is come to save us!". I think that needs to be celebrated with something of a different character than a concessionary birthday cake on Christmas morning, squeezed in before the present-opening and otherwise secular-influenced festivities.
On Christmas, we are presented with the Incarnation of Christ - the fact of God made Man - a crucial aspect of our salvation. While the moment of Christ's birth as Man had an exact historical date, Christ Himself is eternal and uncreated. The Incarnation is ongoing. The recognition of a feast day goes beyond mere remembrance of some past event. It is the active participation of the faithful in a divine reality.
The term "Jesus' birthday" focuses only on Christ's human nature - the birth of a particular baby in Bethlehem. But Christmas is meant to celebrate the truth of the Incarnation - the unimaginable condescension of our God Who became one of His creatures. When calling it His "birthday", there is no recognition of Christ's divine nature. "Jesus' birthday" is a celebration of a long-past historical event, which had a definite beginning and end. "Christmas" is the contemplation of the ineffable mystery of the Incarnation, which is eternal.
I know this might all sound nit-picky. Is it really a big deal if people use a term that doesn't recognize the full reality of Christmas? I would argue that it is. Sloppy wording leads to sloppy thinking and in turn, possible error or loss of faith.