Little Witches (1996)

A group of girls stay at their Catholic boarding school over the break because they have horrible parents who have better things to do than to see their kids.  Well what's a bunch of teenage girls to do except sneak out at night, steal candles from the church, and trespass through the hole in the wall where construction workers found a secret walled up chamber with a dead body inside? And did I mention they're going to hold a seance to figure out who died and why?

Inside the mystery chamber, the girls flit around until one of them finds an old book which is written in Latin.  They figure it must be written by the Illuminati - not the real Illuminati, but a secret group formed at the school in the early 1900s.

They decide it would be a fabulous idea to read the spells and call forth whatever the hell kind of demon they can summon.  This involves all the girls taking off their clothes since apparently the spells won't work with modern clothing.  

As with all movies involving seances and conjuring up either monsters or the dead, this is a bad idea.  There's a silly looking monster, girls who are under control of something evil, and a construction worker who takes his shirt off and ends up helping the good girl whose name is Faith (of course it is).  There's also a guardian who is tasked with making sure no one calls forth the evil. No one shall ask why she just doesn't take the book of Latin evil spells rather than writing warnings in Latin inside the chamber. Do you really think teenagers are going to listen when you say, hey kids don't read aloud from the book that conjures the demon?