I don’t know what Mel Gibson’s budget for The Passion was, but he used no real “stars” and it made IIRC about a billion dollars in the end. Same with Easy Rider. It cost 700,000 dollars to make, but is now one of the most profitable movies ever to hit screens. If you have a good movie, you’ll make money, case closed.
IMDB shows an estimated budget of $30 million for The Passion of the Christ.
Incidentally, it had it's network television debut recently when TBN (Trinity Broadcasting Network) showed it uncut and commercial free. Regardless of what one thinks of TBN, they do air some fine pictures such as Facing the Giants, a very uplifting film.