Does anyone know the name of a lesser known horror movie from the I think the 80's?

[Eli]

I can't remember a lot of the details except for the ending. The cast consist mainly of a group of teenagers, a little boy, a little girl, and an older man. Some sort of evil has invaded their town (can't remember what) and the guy knows how to get rid of it, but needs a female virgin to read something from this book that he has, which is in a different language. So the whole group is outside, and its the climax of the movie, something is happening in the sky and they ask the teen girls who is still a virgin, and one of the girls says she is, so she starts to read from the book but nothing happens, so one of the friends asks her if she really is a virgin and she says something like "Brad (or some other name) didn't count" so they groan and then the little boy points to the little girl and says "Is she a virgin?" and the guys says yes and takes the little girl on his lap and reads the book for her to repeat and it works and the wind stops, the sky clears and all is well.