I must admit it was hard getting over my hemisphere-ism, to imagine spending Christmas in the sun. (Tim is Australian)
I celebrate Christmas without qualms about its being a "religious holiday". The vast majority of the traditions come from pagan religions, not Christianity. Most cultures have celebrated the winter solstice with lights and a feast as a way to remind us that spring and summer will come again. Exchanging gifts comes from the Roman solstice holiday, Saturnalia. Even the date, December 25th, was borrowed. It was the alleged birthdate of Mithras, the Persian sun god, and a popular diety in the 4th century AD. For more of the pagan roots of Christmas, check out http://www.zenzibar.com/articles/christmas.asp (this was the first site I found with a decent list, I'm sure there are plenty more).
Some contemporary traditions are even condemned in the Bible. My favorite Bible verses for this time of year are Jeremiah 10:2-5:
2Thus saith the LORD, Learn not the way of the heathen, and be not dismayed at the signs of heaven; for the heathen are dismayed at them.
3For the customs of the people are vain: for one cutteth a tree out of the forest, the work of the hands of the workman, with the axe.
4They deck it with silver and with gold; they fasten it with nails and with hammers, that it move not.
5They are upright as the palm tree, but speak not: they must needs be borne, because they cannot go. Be not afraid of them; for they cannot do evil, neither also is it in them to do good.
That makes this Christmas tree all the more ironic.