Just a thought

Many people that are religious, be they Catholic, Christian, ect. question my celebration of Christmas when I am, in fact, an atheist. I won't deny that I do celebrate Christmas- I do give gifts, I do tell people "Merry Christmas." I claim that I only do it because that's what I was brought up to do around Dec. 24th and that it really holds no significance for me. This usually doesn't sit well with them, as it reeks of hipocracy or something like that. With that in mind, why do most Americans celebrate Halloween? We're not pagan worshippers of undead spirits, correct??