The Devil Rides Out (U.S. title: The Devil's Bride)....there is also a giant spider if that helps?

 Along with Quatermass and the Pit this is one of my all time favourite horror films!

Based, as a few other movies were, on the books of Dennis Wheatley -a man who stated publicly that witches (actually Satanists)  possessed dark powers. Christopher Lee also warned of getting involved in Satanism (making it clear not regular Wiccans)