Christmas trees are mentioned in the Bible.
Not only mentioned, but prophesied thousands of years before they would become a part of Christmas celebrations. Not only were they predicted, but they were condemned by the prophet Jeremiah:
Thus says the Lord: “Learn not the way of the nations, nor be dismayed at the signs of the heavens because the nations are dismayed at them, for the customs of the peoples are vanity. A tree from the forest is cut down and worked with an axe by the hands of a craftsman. They decorate it with silver and gold; they fasten it with hammer and nails so that it cannot move.Jeremiah 10:2-4 (ESV)