But there are such things as a movie you don't have to buy a ticket to see.
There will be free screenings of The Nativity Story in 30 cities around the country next Tuesday evening. Some theaters will have room even if everyone who's reserved a free ticket comes, so they're opening those up to everyone who shows up (up to theater capacity, of course).
If you're interested, I'd recommend contacting the promoters to see whether the place you'd go has unclaimed tickets. If so, show up early and you might get in.
NOTE: I don't know any more than you do about the movie itself.