The question is a little confusing. The answer is neither. Celebrating Christmas, is looking at one important part of the Christian faith, which cannot be called a cult. Some may try, but Christianity is certainly a religion that is divided into a number of churches that preach and practice the same ultimate message, of God Creating the world, sending his Son Jesus to spread the word and the die on the cross that we may know salvation. He was born of a Virgin, chosen by God. After his crucifixion, he rose from the dead and walked the earth again.
I am not even going to try and describe a cult because I do not want a back and forth argument about what a cult is. To those that have different opinions, I ask that you write your own answer instead of commenting on this. The chain of comments to answers is making the question section look like the forum section of Hub Pages.