Stay with me here. It's a Christmas movie since it falls into the last of my four categories of Christmas movies:
1. Portrays the Birth of Christ - Sadly, the smallest category. The only one I can think of off the top of my head is Little Drummer Boy. At least A Charlie Brown Christmas has Linus reading from Luke 2:8-14.So the last category is why someone can pick Gremlins as their favorite Christmas movie (they were bought as a Christmas present).
2. Deals with Christmas Symbols - This is probably the largest category and includes any movie having to do with Santa, Rudolph, Frosty, and the like. Miracle on 34th Street is usually everyone's favorite in this category. In TV shows, I sort of like those stop-motion shows from childhood.
3. Deals with the Christmas Spirit - This is probably the second largest category since it can make everyone feel good without actually bringing religion or Christ into the equation. Movies like It's a Wonderful Life fall into this category, as do the dozens of adaptions of "A Christmas Carol".
4. Takes Place at Christmas Time - These are movies that take place at Christmas or use Christmas elements at plot drivers, putting Die Hard squarely in this category (the set-up takes place at a Christmas party).