A gnostic mass is like a play that people do in a special room called a temple. It’s based on something called the Thelemic religion. During the play, people wear special clothes and say special words. The play has different parts, kind of like a story. Some parts are serious and some parts are fun. People usually do the play at night and it might feel like a party, but it’s really a religious thing. Some people believe it helps them learn about themselves and feel connected to the universe.