So how did we end up celebrating a wintry white Christmas? The church only settled on a Dec. 25 Christmas in the fourth century. The standard explanation is that the early church conflated its celebration of the Nativity with pre-existing pagan festivals. Romans had their Saturnalia, the ancient winter festival, and northern European people had their own solstice traditions. Among the features: parties, gift-giving, dwellings decorated with greenery.
But even to some Christians, Christmas has always seemed like a version of a pagan feast - and therefore unworthy of observance. The early church father Origen argued against celebrating Jesus' birthday: "It is only sinners like Pharaoh and Herod who make great rejoicings over the day on which they were born into this world." The Puritans of 17th-century Massachusetts famously banned the holiday, in part because they found no Biblical authority for celebrating the Nativity on Dec. 25. (They also feared the Saturnalia-esque disorder and rowdiness that seemed to go with the holiday.) Quakers, too, abstained from celebrating. Harriet Beecher Stowe has a character in her 1878 novel "Poganuc People" explain why his family doesn't observe Christmas: "Nobody knows when Christ was born, and there is nothing in the Bible to tell us when to keep Christmas."
See "Link to External Source Article" below to read further.
Well, now that the question is out there, you might be interested in knowing that The Urantia Book gives Jesus' date of birth as August 21, 7, B.C.
Here's a really good explanation of the reasoning and logic of this date. And the piece also explains why we celebrate Christmas on December 25. The author is Chris Halvorson
You'll read some things about the pagan god Mithras in Chris' article, also. Mithras was a popular god of Jesus' day, and Jesus was fully aware of that. One has to wonder whether Jesus adjusted himself and his purpose in favor of what The Urantia Book calls "the Iranian savior-hero" in certain ways in order to appeal even more to the people. But where Mithras was warlike, Jesus became the Prince of Peace and revealed the God of love. You can read about the Mithraism/Christianity connection HERE and decide for yourself