Early Christians did not attempt to Christianize Christmas. They offered and counter celebration to the pagan holiday of the winter celebration of the Invincible Sun.
Christmas or (Christ Mass) was designed as a spiritually edifying holiday to celebrate the first advent or the incarnation of the Lord Jesus Christ.
Listen to what Colossians chapter 2 says, “16 Therefore do not let anyone judge you by what you eat or drink, or with regard to a religious festival, a New Moon celebration or a Sabbath day. 17 These are a shadow of the things that were to come; the reality, however, is found in Christ. 18 Do not let anyone who delights in false humility and the worship of angels disqualify you. Such a person also goes into great detail about what they have seen; they are puffed up with idle notions by their unspiritual mind.”
A lot of people say they don’t celebrate Christmas because it is pagan. Yet these same people use the internet to criticize people who celebrate Christmas. And the internet is even more pagan than Christmas. So if you can use the internet for spreading the Gospel. Why can’t Christians use Christmas to focus on His birth?
“For unto us a child is born, unto us a son is given: and the government shall be upon his shoulder: and his name shall be called Wonderful, Counsellor, The mighty God, The everlasting Father, The Prince of Peace.” (Isaiah 9:6)