Yeah, a "nice little tradition" that has been celebrated ever since Jesus was born, and has been celebrated on Dec. 25th for nearly 1,700 years.
"but it's not biblical."
Christmas is the celebration of Jesus Christ's birth, and you're claiming the celebration of His birth isn't biblical? This is a simply amazing statement, please read below and find out just how wrong you are.
"---the angel Gabriel was sent from God---to a virgin--and the virgin's name was Mary. He said to her, "Hail, full of grace, the Lord is with you!" ---behold, you will conceive in your womb and bear a son, and you shall call his name Jesus. He will be great, and will be called the Son of the Most High--- and he will reign over the house of Jacob for ever;---therefore the child to be born will be called holy, the Son of God". (Luke 1: 26-35)
"In those days Mary arose and went with haste into the hill country, to (visit) the house of Zechariah and greeted Elizabeth. And when Elizabeth heard the greeting of Mary, the babe (John the Baptist) leaped in her womb; and Elizabeth was filled with the Holy Spirit, and she exclaimed with a loud cry, "Blessed are you among women, and blessed is the fruit of your womb, (Jesus)!--- For behold, when the voice of your greeting came to my ears, the babe in my womb leaped for joy". (Luke 1: 39 - 44).
And the angel said to them---I bring you good news of a great joy which will come to all the people; for to you is born this day in the city of David a Savior, who is Christ the Lord. ---And suddenly there was with the angel a multitude of the heavenly host praising God and saying, "Glory to God in the highest, and on earth peace among men with whom he is pleased!" (Luke 2: 8 - 14).
"When they (three Kings) had heard Herod they went their way; and lo, the star which they had seen in the East went before them, till it came to rest over the place where the child Jesus was. When they saw the star, they rejoiced exceedingly with great joy; and going into the house they saw the child with Mary his mother, and they fell down and worshiped him. (Mathew 2: 9 - 11)
The date is apocryphal, at best.
There is no command in the New Testament to celebrate the birth of Jesus, nor is there even any mention of any such celebration, and certainly not on the date of pagan holiday.