Good movie.
It is essentially the coming of the New Testament into the Old Testament world.
The world is full of violence. Needless violence. And then someone comes along who makes a difference through actions of caring for others. No one just 'stands in the background' to be used and abuse anymore, as slaves and women were in the Old Testament/Pagan days of our world. Not to say that we don't have violence in our world but at least we have a chance at salvation (at least from the Christian perspective). At the end of the film Guy makes it to Paradise, showing the others that it can be done.
The sub-text is amazing. One of the few movies I have seen in the last few years that actually offers up a chance of hope. It is just presented in an incredibly silly way; a video game world where they shoe-horn in gamer dialogue. Feels very silly.
But I was struck by something when I was watching it. Imagine that you were Guy and someone came to you telling you that your world was totally fabricated, a playground for 'higher beings.' But there was something greater than the normal life that you were living every day. That is essentially was true religion is; seeing more to the world than what is actually presented to you.
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If that line of thinking doesn't work for you, you could even look at this from a Jungian point of view. The main character, Guy starts in semi-unconscious state. He is like an animal who just works and sleeps, never having any higher thought. Then he meets his Anima, a female figure who leads him into a higher level of consciousness. He begins to see the way that the world works. He travels down a path of self-fulfillment before coming to face his 'shadow.' This would be the bodybuilder character, who is everything that Guy is not. A violent character who uses violence to solve his problems, something that Guy has largely not done. He has to have a very cliché moment in which he digs down deep and rises above, but because he does that he is able to pass onto a higher level of consciousness.
His journey over the bridge and into paradise could be a symbolic representation of achieving the Self; the highest ideal we have for ourselves.
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You could even look at it from a classically Norse Pagan perspective. The world is falling apart. It is violent. It used to be good. But now it is bad. Then there is a great conflict and there is a hero who survives, leading his people into the next world which is rejuvenated as the Earth is in spring. This new world is amazing and shepherded by great heroes.
EDIT: You can tell they truly make it to Paradise at the end because, Allah be praised, there are no more banks. Therefore no more usury. Truly they were delivered.