“The early Christian community distinguished between the identification of the date of Jesus’ birth and the liturgical celebration of that event. The actual observance of the day of Jesus’ birth was long in coming. In particular, during the first two centuries of Christianity there was strong opposition to recognizing birthdays of martyrs or, for that matter, of Jesus. Numerous Church Fathers offered sarcastic comments about the pagan custom of celebrating birthdays when, in fact, saints and martyrs should be honoured on the days of their martyrdom—their true “birthdays,” from the church’s perspective.”

The precise origin of assigning December 25 as the birth date of Jesus is unclear. The New Testament provides no clues in this regard. December 25 was first identified as the date of Jesus’ birth by Sextus Julius Africanus in 221 and later became the universally accepted date. One widespread explanation of the origin of this date is that December 25 was the Christianizing of the dies solis invicti nati (“day of the birth of the unconquered sun”), a popular holiday in the Roman Empire that celebrated the winter solstice as a symbol of the resurgence of the sun, the casting away of winter and the heralding of the rebirth of spring and summer. Indeed, after December 25 had become widely accepted as the date of Jesus’ birth, Christian writers frequently made the connection between the rebirth of the sun and the birth of the Son. One of the difficulties with this view is that it suggests a nonchalant willingness on the part of the Christian church to appropriate a pagan festival when the early church was so intent on distinguishing itself categorically from pagan beliefs and practices.

“Christmas, Christian festival celebrating the birth of Jesus. The English term Christmas (“mass on Christ’s day”) is of fairly recent origin. The earlier term Yule may have derived from the Germanic jōl or the Anglo-Saxon geōl, which referred to the feast of the winter solstice. The corresponding terms in other languages—Navidad in Spanish, Natale in Italian, Noël in French—all probably denote nativity. The German word Weihnachten denotes “hallowed night.” Since the early 20th century, Christmas has also been a secular family holiday, observed by Christians and non-Christians alike, devoid of Christian elements, and marked by an increasingly elaborate exchange of gifts. In this secular Christmas celebration, a mythical figure named Santa Claus plays the pivotal role. Christmas is celebrated on Sunday, December 25, 2022.”

https://www.britannica.com/topic/Christmas

You can stick you head in the sand and sing “La La La” but it is. Evidently. Per full blown credible sources.