I figured I would weigh in on the Chuck debate...
The way I see it, there are 3 options for how we can answer the question:
"Who was Chuck Shurley?"
3. A Prophet
Let's take a closer look:
In our final moment with Chuck, he was in a crisp white shirt, his glasses no longer needed, and he had a satisfied smile on his face. He told us that the Winchesters had been tested, and that they had passed. Then he disappeared in a golden light.
The logical conclusion - and the one that everyone on set apparently operated from - was that Chuck is God.
Interestingly enough, Chuck actually said when he was first introduced in S4 that he must be a God - a cruel and capricious God. Dean quickly informed him that he was NOT God. Still, Chuck apologized for the physical beatings, and the bad writing.
In an interview, Rob Benedict actually said that Chuck probably viewed Sam and Dean as sons...because he felt that he had a hand in creating them, and that he cared for them. Now, that's the actor talking, not the character - but what I found interesting was that this was from an interview just before Rob saw the finale script. Did he know something already? Or was this coincidence?
The other issue is Dean's amulet. Castiel informs us in S5, that Dean's amulet is also secretly "God-EMF" and that it will grow hot in God's presence. Problem: Dean was wearing the amulet when he first met Chuck, and nothing ever happened. Now, one could argue that God is God, and if God doesn't want to be found, then "magic amulet or not", you aren't going to find Him. The other argument is that Cas was fed bad information from the other angels to send him on a wild goose chase so that he wasn't flanking the boys and helping them too much.
Chuck gets a call and answers the phone expecting a "Mistress Magda" - to which Dean responds that Chuck really has a "virgin/hooker thing" going on. Mistress Magda, of course, is a reference to Mary Magdalene who was a prostitute and also good friend of Jesus. So much so, that there's been speculation that Jesus and Mary Magdalene could have been a little more than friends - by a select few, at least.
Now, in Christianity, Jesus = God. Jesus is God the Son, or God Incarnate, or if he is his own person, he is of equal deity status as God. So, if you are a Christian, me saying that Chuck is Jesus is just the same as me saying that Chuck is God. Well - you might point out that if Jesus were on earth, it'd be the Second Coming, which would signify the Apocalypse - but, umm...that kind of fits too.
Supernatural doesn't really follow along with any one religion though - and this is where Chuck being Jesus actually opens up the field for all sorts of different interpretations of what that means.
For instance, in Judaism, Jesus was just some dude. He was not even a prophet. Worse yet, he may have been a false prophet - deliberately leading good Jewish men and women astray. So, maybe Chuck was just some dude, like we thought he was all the time! And maybe he was leading us astray with his tales of good looking boys who live outside the law.
In Islam, however, Jesus is recognized as a prophet. Paving the way for Mohammad - who was awesome and way better than Jesus. (So awesome, that trying to draw a picture of him is an exercise in futility, because that much awesome cannot be reproduced in the art of man, and you shouldn't even try, because you will never do it justice). In this case, Chuck = Jesus, is Chuck = Prophet. Actually, in Islam, Jesus is even more special than your regular run-of-the-mill prophet, because he's going to come down at the end of times and fight off the Anti-Christ. Woot! Chuck vs. Jesse! That'd be an extremely bizarre fight.
The interesting thing about Islam though, is that they believe that Jesus ascended bodily to heaven, WHILE HE WAS STILL ALIVE. He did not die. He was not resurrected. He just went to heaven when his job was complete. Sound like someone we know?
In other religions...Sikh, Buddhism, Baha'i...Jes
Like I said, Supernatural never follows ONE religion above others. In the Supernatural universe, all religions, beliefs, myths, and lore exist simultaneously with each other. You can have a room full of gods with opposing world-views and it doesn't matter. So, if Chuck is Jesus, which interpretation of Jesus is he? Probably a little bit of each - not quite God, not quite your run-of-the-mill Prophet either.
Maybe you liked Chuck as just the prophet: He was certainly convincing with his nervous behaviour, the headaches and the dreams, the way he allowed Zachariah to push him around, the way he was always slightly scared of Sam and Dean, the way he got a crush on Becky....Was God/Jesus really that good of an actor?
Maybe what we saw at the end was just a prophet ascending to heaven when his job was complete (as prophets are wont to do). Maybe, like everything, Chuck saw it coming. He knew his time was coming to an end, that Heaven did not need him to write the story anymore - that he was going to get his reward. Certainly, one would not want to show up at the gates of heaven in one's bathroom and boxers? So, he puts on a crisp white shirt before he types those final lines. And he smiles, because...well, I don't know about you, but when I finally finish a writing project, I'm pretty damn happy - whether or not the story had a happy or sad ending.
Let me know what you think...