Why does Christmas music make my heart be filled with such overwhelming feelings? Why do I feel like crying every time I hear particular hymns? I haven't given much thought to the question, but I suspect that this is due to the fact that the sheer beauty of these hymns meets the humble and, at the same time, majestic nature of this particular feast.
In these hymns, human creativity and musicality seems to be in awe before the extraordinary event of the birth of Jesus, before the miracle of God becoming man; and we, humans, strive to achieve our very best in expressing, in word and music, our gratitude and love towards God; this is why Christmas music is often a miracle of ethereal beauty, sweetness and heavenly serenity. There is no other music that can have this power. There is no other music which can have such a transformative effect on one's heart.
Christmas music is mostly vocal music - and the reason is simple: people need to express the happiness, need to share their feelings before the Event - and there is no greater way to express musically your feelings than through singing! The words of these hymns are not to be ignored - one often comes across poems of deep theological meanings.
So, Christmas musis seems (to me) to encompass all that is meaningful in this life: love, humility, beauty.