I don't celebrate Halloween, Christmas, Easter nor any other religious day.
(I am willing to fall for that so here it is) :
Halloween being an old pagan festivity, it's kind of a 'royalty free' holiday... Xmas and easter too, come to think of it, they've just been recycled by christianity. I personnaly prefer their pagan origin, and that's how I celebrate. Holidays are just excuses to do something out of the ordinary routine, anyways. Playing dress-up and giving gift to friends and family for no reason, I like it.