“Christmas” is a shortened form of “Christ’s mass”. Today, the popular way to say it is CHRISTMAS. Christmas is the annual festival (25th of December) of not only christian, catholic followers but also the whole world celebrating the birth of Jesus Christ which has been written in New Testament Author Luke.
Referring to Wikipedia, one of the most trusted source, Christmas is an annual festival commemorating, celebrating the birth of Jesus Christ, observed primarily on December 25th as a religious and cultural celebration among billions of people around the world. A feast central to the Christian liturgical year, it is preceded by the season of Advent or the Nativity Fast and initiates the season of Christmastide, which historically in the West lasts twelve days and culminates on Twelfth Night; in some traditions, Christmastide includes an octave. Christmas Day is a public holiday in many of the world’s nations, is celebrated religiously by a majority of Christians, as well as culturally by many non-Christians, and forms an integral part of the holiday season centered around it.
The traditional Christmas narrative, the Nativity of Jesus, delineated in the New Testament says that Jesus was born in Bethlehem, in accordance with messianic prophecies. When Joseph and Mary arrived in the city, the inn had no room and so they were offered a stable where the Christ Child was soon born, with angels proclaiming this news to shepherds who then further disseminated the information. Although the month and date of Jesus’ birth are unknown, the church in the early fourth century fixed the date as December 25.
In New Testament by LUKE, the Author describe the history details of Jesus Christ’s Birth
Original Quote of Luke Chapter 2, sentence 1 to 20
2 In those days Caesar Augustus issued a decree that a census should be taken of the entire Roman world. 2 (This was the first census that took place while[a] Quirinius was governor of Syria.) 3 And everyone went to their own town to register.
4 So Joseph also went up from the town of Nazareth in Galilee to Judea, to Bethlehem the town of David, because he belonged to the house and line of David. 5 He went there to register with Mary, who was pledged to be married to him and was expecting a child. 6 While they were there, the time came for the baby to be born, 7 and she gave birth to her firstborn, a son. She wrapped him in cloths and placed him in a manger, because there was no guest room available for them.
8 And there were shepherds living out in the fields nearby, keeping watch over their flocks at night. 9 An angel of the Lord appeared to them, and the glory of the Lord shone around them, and they were terrified. 10 But the angel said to them, “Do not be afraid. I bring you good news that will cause great joy for all the people. 11 Today in the town of David a Savior has been born to you; he is the Messiah, the Lord. 12 This will be a sign to you: You will find a baby wrapped in cloths and lying in a manger.”
13 Suddenly a great company of the heavenly host appeared with the angel, praising God and saying,
14 “Glory to God in the highest heaven,
and on earth peace to those on whom his favor rests.”
15 When the angels had left them and gone into heaven, the shepherds said to one another, “Let’s go to Bethlehem and see this thing that has happened, which the Lord has told us about.”
16 So they hurried off and found Mary and Joseph, and the baby, who was lying in the manger. 17 When they had seen him, they spread the word concerning what had been told them about this child, 18 and all who heard it were amazed at what the shepherds said to them. 19 But Mary treasured up all these things and pondered them in her heart. 20 The shepherds returned, glorifying and praising God for all the things they had heard and seen, which were just as they had been told.
In short, Christmas is the annual festival (25th of December) of not only christian catholic followers but also the whole world celebrating the birth of Jesus Christ which has been written in New Testament Author Luke.