The MPAA gives a PG rating to a Christian-themed film because its evangelistic message might possibly be offensive to some.
Hey, here's a news flash for ya - the Gospel IS offensive. Nobody likes to be told they're going to Hell and need Jesus to be saved.
Nobody likes to be told they have cancer and need surgery, either.
Frankly, I wish they'd given the film an R rating - then maybe more kids would sneak in to see it.
UPDATE: Here's a related post (ht:HH) on "preachy," overtly Christian movies. He's got a point.