In ancient times people had mid-winter festivals. They believed that the festivals would help the sun to return after the long winter. In the year 440, the Christian Church decided that the birth of Christ should be celebrated every year on 25 December. Christians started to include some of the mid-winter festival traditions in their Christmas celebrations, including decorating their homes with green plants. Today, a Christmas tree and other plants such as holly are still used to decorate many homes in December.