“It’s obviously about Christmas, but for me, it’s a Halloween movie,” he said. “Growing up, Halloween was my favorite night of the year and Christmas was a troublesome time. Into my adult years, it was a time where a bit of a dark cloud would follow me around – probably carrying over from my childhood until I had my own kids – and then I developed a new, brighter view of Christmas.”
He went on to say that Jack, who he also provided the singing voice for, was always a character he very strongly related to.
“I also felt very close to Jack Skellington’s plight because I knew what it was like to be the king of my own little world, and to want out of that world and want something else,” he said. “So I felt very close to the holiday of Halloween, but also very close to Jack and what he was going through.”
Source : https://www.distractify.com/p/is-the-nightmare-before-christmas-a-halloween-movie