It all depends on HOW you celebrate Christmas.
If you celebrate it by decorating a tree with lights and tokens, burning a fire, singing secular songs, spending lots of money on material things, and getting drunk, then I agree with you. These are pagan traditions. I'm frustrated by how many of them have crept into the church.
But honoring a day for Jesus' birth, as it is described in the Gospels of Matthew and Luke, there is nothing wrong with that. True, we don't know what day it was. It probably wasn't December 25. I know that day was picked to compete with the Pagan festivals. But it was picked, and there it is. Why not celebrate it then? It is really cool symbolism: in the darkest time of the year, Christ, the light of the world, comes as a baby. Singing hymns that praise God and his son Jesus, worshiping the King who was born in a lowly cattle shed, the boy who was born in the City of Bread, to be the Bread of Life. You know, I see nothing wrong with celebrating Christmas as long as you focus on Jesus.
And, if you want to buy a tree and put lights on it, and tokens, I have no problem with that. Call it a holiday tree, or whatever .... There is no law in the Bible that says we are not allowed to celebrate civic holidays. I see celebrating the Solstice with the secular traditions (trees, santa, etc.) no worse than celebrating, say, Independence Day or Memorial Day. These holidays are certainly not religious in origin, but that doesn't mean they are sinful, and we are not sinning to partake in the nation's traditional celebrations of gift exchanges, social gatherings, etc. As long as you don't pretend that it's a religious celebration, I have no problem with it.
Keep the sacred sacred and the secular secular, and there really is no problem here.