Christmas Question

I've been pondering this question over the past few holidays, and I'm going to go public with it, hoping that you can help me solve the puzzle. Here it is:

If Christmas is about the birth of Jesus, then why don't more churches put up displays of the nativity scene on their lawns and in the sanctuary buildings instead of putting up Christmas trees?

I'm not even sure that there is a nativity scene set at our church, but I know that there are multiple Christmas trees. This kind of bothers me, really, and I wish that there were more places that were willing to display a nativity scene during the Christmas season.

Don't get me wrong, I love Christmas trees, and I am sitting with our tree twinkling in the corner as I type this. But, our nativity scene is also just a few feet away. Because really, Jesus is what the Christmas holiday is all about.