One of the first groups of people to start the Christmas tree tradition were the Germans when devout Christians brought a tree into their houses and decorated it. But the tradition goes back into ancient times.
Lots of people that were alive in the ancient times believed in gods and a lot of these people also believed that the sun was a god or the work of a god. People from these times also believed that evergreen had special properties.
Ancient Egyptians believed that the sun was a god called Ra and that winter was when Ra was sick and ill. The Egyptians put evergreen on their houses to celebrate Ra’s return in the Summer.
History of Christmas trees, http://www.history.com/topics/history-of-christmas-trees accessed 12th December 2013