Pagans, more-or-less by definition, are not Christians, so why would we celebrate Christmas? Well, followers of paths such as Druidry, Wicca, Heathenism, etc., mostly live in countries that are nominally Christian, and in which Christmas is a pretty big deal. So most Pagans celebrate Christmas in the same way that most Christians do, as a festival of consumerism, over-eating, family gatherings, gift-giving and office parties.
it is my experience, in the hundreds of dialogues I've held with adolescents, that no one is more open and honest and piercing than than they are when it comes to investigating questions such as: Who am I? Who can I become? What do I want to be when I grow up? It behooves the rest of us, at every age and stage, to hold inquiries on such questions with them, so we can be privy to their keen insights.