Meh. I don't really think not believing in the root causes of the day makes them completely meaningless. I still celebrate because it's fun to celebrate. Let easter be about welcoming in the new spring and summer. Christmas be about giving and wrapping up the year. Just take the days as days to enjoy with your family.
Both Easter and Christmas dates were stolen by the church anyway from older religions, so you could even say that Christianity took the original meaning out of them too.
