I could not tell if the filmmaker was making this a Christian Allegory or mocking Christian allegories. There is so much of the religious in this movie.
Superman tells Lois at one point. "You said the world doesn't need salvation but why do I hear the world calling out for a savior."
There is the scene about the Father being the Son and the Son being the Father.
The scene where Superman is stabbed in his side and his beating were straight out of the passion.
There is just scene after scene where Superman is shown as a Christ figure and it isn't a mistake these things are there intentionally. Despite the fact that this was made by serious leftists and religion haters I felt a very religious reaction to the movie. I think maybe the film maker tried to mock Christ and in doing so created a movie that really uplifts. Much like Lion the witch and the wardrobe is allegory the story seems so right.
Good observations. I don't know the background of the director and screenwriter, but clearly religious symbolism and imagery in movies tends to be popular, and powerful, whatever their motives.