Scary guy at school...please help!?

Omg, this dude at my school, let's call him bob. Bob was new to our school and he never came. I go to a Christian private school and nobody does drugs or anything ( that I know of) I was talking to him and he openly said he does heroine(do you "do" heroine?!) and like marijuana and he smokes and crazy stuff. He also got out of class one day to attempt to summon a wood imp doing some ritual in the woods. He seemed so serious and confused when people thought he was crazy. One day he put a message on Facebook saying he was going to kill all the Christians at our school. (im a Christian that goes to his school, eek!) and he texted my friend saying he was going to kill everyone at our school. Obviously he was suspended. If he isn't lying, then what type of crazy person would do that? Im scared he will like come to my house and kill me or something! ( btw I am a freshman in high school)