Do you want a fight? 'Christmas' as a Christian festival is a completely made-up confection ie nicked from a mixture of the Celtic/Norse/Roman midwinter festivals.
And anyway, WTF has it got to do with you whether or not other people celebrate? How does it actually affect your celebrations?
I know that plenty of perfectly nice, likeable, sensible people just happen to have religious faiths, but there do seem to be an awful lot more utterly bucketheaded Christians around these days.