Jack Slater IV takes place at Christmas with the line delivered early "this is a hell of a way to spend Christmas!"
So, I guess that makes Last Action Hero qualify as a Christmas classic alongside Die Hard and Lethal Weapon.
You got that wrong. It was Jack Slater 3 that takes place at Christmas. But it's only a small part of the movie and the sequel Jack Slater 4 that Danny watches and goes into has nothing indicating it takes place at Christmas.
If you think it is cause of the beginning , then by your logic, the original Jumanji movie, Forrest Gump, and Toy Story are Christmas movies because a small tiny bit of those movies takes place at Christmas.