Here we go again. Why is it Catholic holidays arouse such skepticism?
When learning about originally Catholic Holidays go to Catholic sources. Catholic Encyclopedia
Put simply Christs birth has been celebrated as early as 200 AD and the 25th of December was recorded as the day of his birth as early as 354 in Rome.
Never let it be said that that means it is accurate or that the debate is over however it did become the accepted traditional day for Christmas throughout the Christian world and the 6th of January (twelve days later) was the traditional celebration of the coming of the wise men.
He gar prote parousia tou kyriou hemon he ensarkos [en he gegennetai] en Bethleem, egeneto [pro okto kalandon ianouarion hemera tetradi] Basileuontos Augoustou [tessarakoston kai deuteron etos, apo de Adam] pentakischiliosto kai pentakosiosto etei epathen de triakosto trito [pro okto kalandon aprilion, hemera paraskeun, oktokaidekato etei Tiberiou Kaisaros, hypateuontos Hrouphou kai Hroubellionos. -- (Comm. In Dan., iv, 23; Brotke; 19)
"For the first coming of Our Lord in the flesh [in which He has been begotten], in Bethlehem, took place [25 December, the fourth day] in the reign of Augustus [the forty-second year, and] in the year 5500 [from Adam]. And He suffered in His thirty-third year [25 March, the parasceve, in the eighteenth year of Tiberius Cæsar, during the consulate of Rufus and Rubellio]."
Is there scriptural reference to back up celebrating Christmas? That depends on whether you believe anything not expressly written didn't happen. There are references in the new testament to Christians being chided for celebrating pagan holidays but never for celebrating Christs birthday (or any other occurrence during his life) its self so we simply don't know how they felt about it based on that. So I subscribe to the belief that if it was fine for the Angels to celebrate it is just fine for me to do so as well.
Luke 2The important part is making sure that is what you are actually doing and not just thinking of yourself or the entire holiday becomes meaningless.
10 And the angel said unto them, Fear not: for, behold, I bring you good tidings of great joy, which shall be to all people.
11 For unto you is born this day in the city of David a Saviour, which is Christ the Lord.
12 And this shall be a sign unto you; Ye shall find the babe wrapped in swaddling clothes, lying in a manger.
13 And suddenly there was with the angel a multitude of the heavenly host praising God, and saying,
14 Glory to God in the highest, and on earth peace, good will toward men.
PS. It seems every time I track down this idea of Catholic holidays being actually pagan I keep coming back to Anglican England as the origin of the belief... hmmmmmm Wonder if there just might have been some bad blood there.