Christmas is NOT ONLY a RELIGOUS event. In fact, Dec 25th was once a pagan holiday celebrating the turning of the seasons, a new year, and a hope and thanks for another yr survived. When the Roman church rose to power they used Dec 25th to celebrate Christ's birthday(even though its in March) b/c Dec 25th was already a Germanic holiday and the Romans thought it might be easier to incorporate this new holiday if it were the same day as an old holiday.

Of course the christmas tree and lots of other christmas traditions we celebrate were founded in Germany waaaaaay before the emergence of Christianity in Europe or Rome.

My whole life I have said both happy holidays and merry christmas. I haven't had anything kosher thrown at my head yet!

EDIT-I also say Happy Festivus, a holiday created by one Frank Costanza.