Movie I forgot

So I remember back in my childhood (15-20 years ago) I remember there's this American movie it's basically a bunch of kids with a boy who got favoured by a demon named ferluci. And later on his parents realized that ferluci stands for Lucifer. The setting is in school where I think there's this ghost house or something I forgot where the devils torment his bullies exactly like the way the by wanted (he writes it in his diaries) but that didn't actually happened because the boy saved them.

At the end of the movie the boy gives middle finger for the bullies but his finger is a wolf claws. And yes I think the boy can change into a werewolf