The Star Trek franchise's impressive lifespan perhaps makes it surprising that the space opera has never engaged with one of the biggest TV tropes, but there's actually a very good reason why Gene Roddenberry's long-running sci-fi saga has never produced a Christmas special. Although the Christian festival has been mentioned in passing and referenced a few times in the movies and TV shows that combined to form the Star Trek timeline, it is never really addressed head-on or with any real commitment.
While this could easily be viewed as a missed opportunity, it wouldn't really make sense to write a Star Trek Christmas episode from a canonical perspective. Instead, the Star Trek TV shows generally tend to sidestep Christmas while supplying the audience with cryptic explanations as to why. Similarly, the Star Trek movies, as a rule, are pretty bereft of festive cheer. That being said, the feature-length productions not including Christmas makes far more sense, but given that many Star Trek shows have adhered to the traditional network TV schedule, it's a little more unusual.
Humanity Being Largely Secular In Star Trek Means Christmas Is No Longer Celebrated
Christmas has been left behind in the world of Star Trek
It's understandable why those on Earth in Star Trek losing their reverent spirituality in the face of scientific advancement would cause Christmas to be sidelined.
Star Trek: Enterprise is set the furthest in the past of all the shows, so if any of the spinoffs were to boast a festive installment, it would be Enterprise. However, the show proves that even by the 22nd century, Christmas isn't acknowledged anymore. The holiday has been relegated to nothing more than a footnote in humanity's history. Of course, in the real world, Christmas isn't always celebrated with religious motivations, but it's understandable why those on Earth in Star Trek losing their reverent spirituality in the face of scientific advancement would cause Christmas to be sidelined.
Star Trek's Alien Races Still Have Religions Celebrations
Humanity appears to be in the minority among Star Trek's various races
One of the biggest separators between humans and the aliens in Star Trek is that those from beyond Earth didn't shed their religious traditions when they took to the stars. Races like the Bajorans, Klingons, and the Ferengi all have surprisingly complex belief systems that revolve around deities, afterlives, and other religious traditions. In fact, the Klingon afterlife, Sto'vo'qor, is softly canonized in Star Trek: Voyager season 6, episode 3, "Barge of the Dead."
Some human Star Trek characters, like Robert Beltran's Chakotay, prove that not all of humanity has abandoned spirituality.
Some of the alien religious celebrations do have some similarities with Christmas, so it could be argued that this is a way of incorporating the holiday into Star Trek while still having it fit in with the franchise's canon. That being said, some human Star Trek characters, like Robert Beltran's Chakotay, prove that not all of humanity has abandoned spirituality. However, many of the religious belief systems in Star Trek, human or alien, are often supplied with a sci-fi explanation that can often justify them as real. This isn't always the case, though.