“I can’t believe Christmas is over,” my dejected daughter said.

I know how she feels: The aftermath of Christmas can feel dreary. Presents have been opened. The tree and lights must come down. Listless January—and, for many, the need to shed holiday pounds—awaits. Christmas—and the breathless anticipation that comes with it—suddenly feels eons away.

A few years ago, as we were putting Christmas stuff away, I realized, No matter what the calendar says, we’re always one day closer to the next Christmas. It’s become something I say frequently.

But far more important than our temporal celebration of Christmas is the spiritual reality behind it:…