Well depends on what you celebrate.
Did you know that Christmas was repurposed from a pagan holiday
as well? In fact in Puritant England, they attempted to ban
Christmas, with the only valid Christian "celebration" being Good
Friday.
Personally I believe such moves, while well-intentioned, miss
the mark. Your faith should be something that transforms the
celebration, not something you need to hide and wall off from the
rest of the world. No surprise that Christianity has been a
religion that repurposed a lot of worldy things, it is I think, the
nature of it.
The only vaild celebrations by people who claim to believe in
G_d are those that G_d has ordained in the bible. The others are
man made traditions which are like you say repurposed by
christianity. This repurposing still does not make it right. Even
if you have faith, celebrating a festival which is considered by
G_d to be unacceptable in His sight still does not make it right.
In the end you have to make the judgement call as to who you
serve.
