But we celebrate Easter as Jesus' resurrection, so it has everything to do with the Messiah.
We celebrate Christmas as the birth of Jesus Christ.
And for us Lutherans, we celebrate Halloween as the day Martin Luther nailed the 95 theses.
In most cases, there's a little bit of pagan tradition. We celebrate Jesus' birth, but we also have presents on Christmas. We celebrate Jesus' resurrection, but we also have Easter Egg hunts and the kids get Easter basket.
The point that I'm trying to make is that just because a holiday has a secular connection to it, even one that might be evil, that doesn't mean we shouldn't celebrate our own way, and it certainly doesn't mean that we shouldn't educate our children about the history of the holiday. We do this with Halloween. If you were to ask my children what All Saints Day is, they can tell you (well, the 12 year old can). Ask him why we celebrate Christmas when we do instead of when Jesus was actually born, and he can tell you.
Avoiding these holidays, or pretending they don't exist is sort of like ignoring that "talk" that parents should have with their kids about sex. Ignoring something does NOT make it go away. Alternative celebrations, such as Harvest Festivals (although these too are wiccan based) or Hallelujah Parties are okay as well, as long as there is instruction as to why they do this rather than trick or treating. Kids naturally get curious...and where would you rather have your child hear about witches and demons, you, or the schoolyard chum?