Christmas is celebrated in December because it's the time of year when the days are shorter and the nights are longer. The holiday has its roots in the pagan festival of Yule, which was celebrated by people in northern Europe to mark the winter solstice. The Christian Church eventually adopted the holiday and used it to celebrate the birth of Jesus Christ. So, the 25th of December was chosen as the date to celebrate the birth of Jesus, which is why we have Christmas in December.