Who's to say really that Religion and religious holidays don't exist in ficticious future setting world, for all we know religion in it's many forms (and possibly more due to the introduction of alien cultures) do still exist on Earth in the 23rd and 24th century where people still go to church, abide by religious commandments and laws etc. Just because the 7-10 people we focus on during the run of each series don't make a mention of most of them or acknowledge them doesn't necessarily mean they don't exist. The average person in the background could, for all we know, be Jewish, Catholic, Protestant or whatever they may be but nobody really needs to know.
Sorry about the rant but it just seems that there's always a post on religion in Star Trek and almost all the time people start arguing about it. I just have to point out though that although I was raised Protestant and went to church with my parents I do not follow religion myself, just believe that it is there for a purpose.
