Yule
The Christian holiday, Christmas, was created by the Christian Romans based around the polytheistic (many Gods) Sun God festival (Sol Invictis) on the winter solstice, and people in northern Europe combined it with their Yule festival.  Yule is celebrated on the 25th of December by most Northern Europeans and the 21st of December, by Wiccans and many non religious groups. For them, Yule is celebrated as the longest night of the year. It is the night when the sun sets earliest and rises latest the next day. The Wiccan ritual includes thanking the Goddess for the past year and asking for a happiness in the year to come.