Yep, Christmas and other festivities are all of pagan origin anyway - they were just conveniently turned into Christian holidays, just like many of the former deities blended into Christian saints, and most people aren't even aware of what the original meaning of the holiday was. It's not like we really know when Jesus was born, is it? So it's hardly a coincidence, is it, that Christmas falls roughly at the time of norther hemisphere winter solstice.
In Serbian/Croatian, Christmas is called Božić, which literally means "little god". Most people would probably assume it's Jesus, unless they have had studied a bit of Slavic mythology as a part of Cultural Studies at the university, like I have, in which case you learn about stuff such as some old Christmas folk songs about the birth of "Božić, Svarožić" - "little god, Svarožić (Svarog's son, little Svarog)" - Svarog being the Slavic Sun god. Basically, it was about the death of the old Sun (god) and the birth of the new, young Sun (god) - winter solstice, when the daylight time is the shortest and then starts becoming longer with each day.
Traditions and especially traditional festivities tend to outlive their initial reason for existence, and it's likewise quite possible than people in the 24th century could celebrate holidays like Christmas regardless of whether they are religious or how they feel about Jesus.
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