When you think of Christmas, you're probably thinking about Santa Claus and presents, not Jesus. In fact, most Christmastime movies and songs are about Santa rather than Christ, the namesake of the holiday. We also have this lore built up around Santa that was created by film studios and retailers hoping to sell more products. Rudolph the Red-Nosed Reindeer was originally made as a coloring book but now it's themes and imagery is what children think of when they imagine the North Pole. To use a wild analogy, it's sort of like how Dante's Inferno became what people think of as "Hell".
Does anyone know of any other religious holidays that have been so thoroughly transformed over time? I'm curious if this has happened to other holidays or if it is just a unique product of American culture and consumerism.