One concept Eliade elucidates is the "Restoration of Primordial Chaos" and the idea that society needs these moments and figures of chaos in order to rejeuvenate its "soul."
Our modern society has largely tamed these chaotic holidays ("Holy days"), but we still have one day that maintains its chaotic nature: Halloween.
This chaotic element is also why some religious fundamentalists oppose its observance: it is a day of "demonic energy" (which is just a synonym for chaos).
Needless to say, for many children, Halloween is the preeminent holiday: a day of excitement and breaking society's norms.
For this post, give one example of how Halloween embodies the idea of chaos. I'll start you off:
The idea of "Trick or Treat" is itself a threat; children are quite literally blackmailers: "If you don't give me candy (the treat), I'm going to do something bad to you (the trick)." This could be egging the house, toilet-papering the tree, or smashing a pumpkin. In other words, for this night (unlike the rest of the year) the kids are in the position of power . . . and they demand chocolate!