Since I don't believe in God it negates me celebrating "religious" holidays. I don't see a point in it and to do so is a form of hypocrisy: "I don't believe in God but am going to celebrate christian holidays"...really hypocrite? That's absurd! I see non-religous holidays as nothing more than rituals charged with social significance that reflects the structure of society and I have no trouble celebrating things like the Fourth of July or Veterans Day. Religious holidays, however, I see completely different entirely. In my subjective opinion, I see belief in a deity as a type of mental defect, a of cognitive distortion in reasoning where people are consumed with anecdotal hasty generalizations supported by confirmatory biases thus, they engage in a host of composition errors purported as "truth." If you want to get technical the notion of faith as expressed by Christianity, or any religion really, relies specifically on abstract notions with no basis in logic or evidence to validate it while producing irrational intransigence (e.g. you are going to hell if you don't believe what I believe).
I mean, claiming that I or anyone else will burn in hell because God will punish us is an ad baculum error in reasoning which makes the argument invalid. In order for that appeal to fear to work one must believe the same thing the religious person does and when people don't, like me, it makes the argument completely invalid and irrelevant. What I find truly sad is that people like that will still try to hold onto that argument knowing people like me do not believe in their conceptualization (delusion really) of God and continue "faithfully" to keep their absurd, erroneous assertions. To me, the moment someone brings a diety into the conversation everything they have to say looses validity and I tend to refrain from any further discourse with them. The real problems that stem from religion, especially Islam and Christianity, is that they cannot respect differences and lash out at anything that is aberrant to their ideology. I respect a person's 1st amendment right to freedom of religion and to believe as they see fit so long as they do not try to dictate my life with their religion; but that never really seems to happen.
That's my opinion on the matter.