There are two reasons why I like Halloween: eating leftover candy (of which there is a lot; my house never gets many trick-or-treaters) and watching Hocus Pocus (Disney, 1993), which is a classic. Other than that, I have never cared much for the holiday, so I’m going to recount something I learned a few years back.
Before Vatican II, the Catholic Mass was said in Latin. The most pivotal and sacred part of the Mass was (and still is) the part where the priest raises the host into the air and says, “This is my body, which will be given up for you.” (Or something to that effect.) In the Catholic tradition, what occurs at that moment is called transubstantiation, which is when the host, an ordinary piece of bread, changes into the body of Christ.
One of the reasons the Protestants split off from the Catholic Church around the time of Martin Luther was because they did not believe that a piece of bread could “magically” become the body of Christ with just a few Latin words spoken by a priest. In Latin, “this is my body,” was “hoc est corpus meum.”
It might be an urban legend, but the phrase “hocus pocus” supposedly came from a butchering of those Latin words spoken in the Catholic Mass. Followers of Martin Luther referred to transubstantiation as nothing more than a “magic trick,” and thus referred to the act of bread becoming Christ’s body as “hocus pocus.” Either way, “hocus pocus” sounded magical and had a nice ring to it, so it stuck around and is still used to this day.