I found an interesting article:
Can the Christian Celebrate Christmas?
Is the Christian free to celebrate a holiday that not only has pagan origins, but also is used by the unbelieving world a promotion of commercialism? In my opinion, it depends.
The Christians must hold his standard of righteousness and devotion to God above those of the world. The Old Testament says that we are to worship God in truth according to the dictates that He has established (Exodus 20:1-4; 24:12-31:18). Christmas was not established by God. In addition, there are no records at all of the early church celebrating the birth of Christ.
On the other hand, there are those who say we have freedom Christ and can celebrate any day we want to. Paul says, "All things are lawful, though not all are profitable" (1 Cor. 6:12).
Should we then participate in the celebration of a festival origins and exceeding commercialism?
It is my opinion that we are free to celebrate the day. This is why.
In the Bible in 1 Cor. 10:23-33, Paul speaks about meat sacrificed to idols. This meat was often sold in the meat market and the question arose, "Should a Christian each such meat?" Paul said in verse 25, "Eat anything that is sold in the meat market, without asking questions for conscience' sake." The origins of the meat were, essentially, pagan. Many animals were raised for the purpose of sacrificing to pagan deities and their meat was offered in the market place. In reference to this Paul said it was okay to eat the meat.
Then in verses 28-29 he says, "But if anyone should say to you, 'This is meat sacrificed to idols,' do not eat it, for the sake of the one who informed you, and for conscience' sake; 29I mean not your own conscience, but the other man's; for why is my freedom judged by another's conscience?" (NASB). Paul is saying that if you are with someone who might be stumbled by your eating meat that was sacrificed to idols, then don't eat it -- not because of you, but because of the other person. In other words, eating that meat won't affect you. The false gods are not real. They have no power.
1 Cor. 8:-7-9 echoes this idea. It says, "However not all men have this knowledge; but some, being accustomed to the idol until now, eat food as if it were sacrificed to an idol; and their conscience being weak is defiled. 8But food will not commend us to God; we are neither the worse if we do not eat, nor the better if we do eat. 9But take care lest this liberty of yours somehow become a stumbling block to the weak." Though this passage requires a bit more examination, it still carries the sense of freedom. And, Jesus has definitely set us free.
However, if you are not comfortable with this conclusion and you don't want to celebrate Christmas, that is okay. You must answer to the Lord.
Sanctification
The Lord, through His sacrifice, has cleansed us of our sins. When we come in contact with Him, it was we who were cleansed. It is not Him who was made dirty. The woman with the issue of blood who touched Jesus (Mark 5:25-34) was made clean. It was not Jesus who was made dirty. Likewise Jesus touched the unclean lepers and cleansed them (Matt. 8:3). Jesus came in contact with many people and it was never Him who was dirtied. It was they who were cleansed.
I think this principle can be applied to Christmas. Yes, Christmas has pagan origins. Yes, it is a highly commercial time. Yes, many do not have their eyes on Jesus. But for the Christian it is a time to reflect upon the birth of our Lord and to celebrate. We are making the day holy.
Source:
http://www.carm.org/questions/christmas.htm