Christmas, a time for excess...

I believe that Christmas at the end of the day is not sustainable at all.
This is due to the vast amounts of electricity used facilitating large amounts of festive decorations, from standard tree lights, to large structures layering the outsides of houses.
Food is also a large issue to consider, as there is always far too much left over, resulting in vast amounts of waste, which would not occur on a regular day of the year, being not Christmas day.

The amounts of packaging on the 'must have' toys and gifts in general also contributes greatly to the unsustainability of Christmas.

Overall I do believe that putting this all aside, Christmas is Christmas, and Christmas has always been known as a day of vast excess and indulgence in luxuries you would not receive during the rest of the year.

Which is why, although Christmas is not celebrated or based on sustainable morals, Christmas is only enjoyed once a year and Christmas would not be the same if these unsustainable morals were stripped away (and you only live once) :)