The tradition of celebrating Christmas in December has its origins in the ancient Roman festival of Saturnalia, which was celebrated around the winter solstice. The Roman Catholic Church later adopted December 25th as the date for Christmas, which coincided with the pagan celebrations of the winter solstice and the birth of the sun god Mithras. Over time, the Christian holiday of Christmas became associated with the birth of Jesus Christ, but the date of December 25th was already deeply ingrained in the culture and traditions of the people of the time.