• Warning: Spoilers
    There seemed to be a lot of these movies, all probably in reaction to "The Exorcist" and "Rosemary's Baby" in latter-seventies. You can add this film to the list including The Car, The Wraith (with a young Charlie Sheen, if memory serves, The Herse and Devil's Rain. The Dunwich Horror... well... it fits in this category, but is almost too good to include. Besides, it at least has Sandra Dee! And now a SLIGHT spoiler warning as this has been mentioned in previous comments...

    The secret family name NOMED was a rather obvious plot hint. If I were marrying someone with that name, one of the first things -I- would probably realize was that it indeed was DEMON spelled backwards.

    I think I would insist on a hyphenated name. Like Susan Cthulu-Smythe or some-such.

    This film would probably be a good selection for a collection of films which are "so bad, they're good."