I still haven't seen the movie (unfortuneately), but from the accounts I've heard from both sides, the worst you could call it would be "Historical Fiction".
Obviously some liberties have to be taken when making a movie about ANY historical event (unless you have first-hand witnesses). However, basically everyone agrees that the man Jesus of Nazareth was crucified, and the manner in which the crucifixion was portrayed in the film is reportedly accurate by the accounts of historians.
The only real debate is whether or not Jesus was (is) the son of God.
Anyhow, I wouldn't force it on anyone. I just hope the people who do see the movie are enlightened in some way.