It's been over thirty years since I've celebrated Xmas myself. That said, I want to endorse everthing Mr Offer said and to suggest you do whatever you damn well please. Keep the tree if you want to. It represents the world ash, Yggdrasil, from which All Father Odin hanged himself for nine days and nights. The holly is a reminder of Loki's perfidity and the slaying of Baldur the Beautiful. If that's good enough for Christians, it can be good enough for you,too, if you want it to be.