Answer: The Bible does not have any direct or explicit statements saying, "Thou will not celebrate Christmas." That said, however, it also does not have a specific text condemning the use of heroin or cocaine either. Most Christians would condemn drug abuse by using the principle that since God's Word condemns drunkenness, it also condemns getting high from drugs. It is in the same sense that Christmas is condemned.
Are there any verses that state what occurs on this great holiday, which is the adapting of pagan customs or practices to worship and honor God, is wrong? These verses, in principle, would apply to holidays such as Christmas, Easter, and Halloween that have most or all of their customs based in pre-Christian worship of false gods.
Applying a principle
One Biblical principle that can be applied to the condemnation of Christmas is in Deuteronomy. God sternly warned ancient Israel what not to do in the Promised Land by stating that following.
. . . do not inquire concerning their (Canaanite and other) gods, saying, 'How did these nations worship their gods? I also want to do the same.' You must not do the same for the Lord your God, because every abhorrent thing that the Lord hates they have done for their gods' (Deuteronomy 12:29 - 31, NRSV).
Notice that Israel was warned not to borrow or adapt the ways pagan nations use to worship a false deity and apply them to their worship of the true God. Sinful pagan customs are not made right by applying them to the Eternal.
Borrowing from the pagans
One of the best examples of what God thinks about humans borrowing and adapting false (pagan) customs (for holidays like Christmas) to use toward worshipping Him is in Exodus 32.
God calls Moses up the mount to receive the Ten Commandments. The children of Israel must wait at the foot of the mountain for him to return. As time passes, the Israelites grow restless. When Aaron, the High Priest, sees this he tells the people to bring him their jewelry so that he can melt it down and make them an idol (shaped like a calf) for them to worship.
God's response to the people using pagan customs to worship him (as is done in Christmas) was swift. He did not accept Israel's worship through the golden calf even though Aaron the High Priest was involved. His anger was kindled toward the people to the point where he was ready to destroy them all (Exodus 32:4 - 5, 7, 10)! It took the personal intervention of Moses to save the people from being completely destroyed (verses 11 - 14).
Customs used to worship false gods that are transferred to the true God, like is done with Christmas and other holiday, are unacceptable since the Bible never compromises with paganism. This is exactly the point the apostle Paul was making in 1Corinthians 10:19 - 22.
What the pagans practiced did not honor the true God in spite of how much sincerity or faith they possessed. The same goes for the customs used in holidays like Christmas and Easter.
How did it creep in?
How did pagan customs and holidays like those involved with the holiday come into the Christian church? They primarily entered through the Catholic Church's efforts to adopt then "Christianize" certain holidays not found in the Bible so that they could attract more people in their pews on Sunday.
The Catholics began to paganize themselves especially after the fourth century A.D. when the Edict of Milan openly endorsed Christianity as a religion. The truth is the pagan festivals celebrated around the time of the winter Solstice have far more to do with Christmas than Christ's birth (which occurred in the fall).