Secular Christmas is kindof meh, honestly. It's basically Thanksgiving again plus obligatory present giving, horrendous traffic, and shopping crowds. I enjoy a good holiday with family, regardless, but I'm also worn out on the commercial themes that have been hanging around since literally before Halloween. I'm sure when I have kids there will be a renewed magic to it, because childlike wonder is infectious.
In contrast, the religious theme is potent and meaningful. It takes a little suspension of disbelief if you're not Christian, but this is true of all myths. I feel no need to disdain Prometheus or the River Styx simply because these things lack literal truth. In the Christian myth, our yearning for absolution is touched by grace and we are made whole again: unfractured, unscarred - a kind of healing that mere time cannot provide. Jesus is the physical manifestation, the personification of grace and forgiveness.
Forgiveness is necessary to sustain any relationship over the long term, including one with ourselves. Because the forgiveness in this myth is perfect, the grace infinite, no one is beyond its reach. However unable you are to accept yourself, or obtain absolution from others, God is still there. It opens a gateway to renewed self-love, and because whole communities believe in this and place God's judgment above their own, it opens gateways to re-acceptance into the community as well. That no one is beyond redemption is powerful, because placing someone beyond redemption makes them incorrigible or worse. This is the ultimate restorative justice, powered by magic/God.
Like the tale of the Boy Who Lived in Harry Potter: there was darkness, and it was sundered by the power of love as manifested in an infant. A mysterious event met largely with relief and gratitude, a bewildering Deus Ex Machina. Who would not be grateful for the sudden respite?
This is not to say that there are no problems with the myth, but on a holiday celebrating it I prefer to put that aside and appreciate it for the worthier parts. We have to live with each other; it may as well be in harmony. Peace on Earth and good will towards men - it all starts with the grace to forgive. The myth has literary meaning that extends into our real lives; Jesus does not have to really exist for this to matter, though that does sound nice.