I see it as similar to the arguments over whether or not "Literature X" is Evil.
In order for literature to be Evil it is not sufficient to simply "depict" Evil - since in order to warn against/castigate/denounce evil - which would be the OPPOSITE of Evil - you must also describe/depict it in some fashion. The Literature must either "advocate" (arguably) or "embody" Evil and/or its tenets/themes to be considered "Evil Literature".
Some literature depicts evil.
Some literature advocates evil. (It can be debated whether or not something that advocates for evil is itself evil.)
Some literature embodies evil (or, if you prefer, "is evil" by definition).
So let's apply this same logic to determining whether a movie (literature) is a Christmas Movie (Evil).
Die Hard depicts Christmas.
Die Hard does not advocate for Christmas or its tenets/themes ("peace on earth, good will to men").
Die Hard does not embody Christmas or its tenets/themes.
Therefore, while Die Hard is a movie that depicts Christmas, it is not a "Christmas Movie." (You could also apply this to a lot of Hallmark movies.)
(The above is not intended to convince you that you're right/wrong, it is merely the description of how I get to where I get. Your mileage may vary, particularly if you disagree with my assumptions.)