Belief forms a very strong central theme in Serenity. At the top of the second act, Shepherd Book advises Mal that he will need such a thing if he is going to go up, successfully, against someone like the Operative. Mal retorts that he has no need for sermons, but Book is careful to make clear that he isn’t talking about God, or any belief in the almighty. He’s talking about just having something bigger than yourself to hold onto, something that will make you keep going despite tremendous adversity. The characters of Serenity have those things, and it’s part of what makes them so endearing. It’s important for good characters to want something, even if, as Kurt Vonnegut said, it’s just a glass of water. But characters that really believe in something can pull you in even greater.
Mal starts out a listless individual, whose belief in something bigger seems to only go so far as whatever will keep his crew fed and his ship in the air. He doesn’t seem to have much honour worth speaking of: he threatens to hand over Simon and River to the authorities very casually and is embarked on a life of robbery. He has no faith in God. He seems to have no love in his life, having been burned in a way by Inara. He was a man who had all those things at one point, but they’ve all been stripped away. It is only when the Alliance starts targeting him and the few remaining people that he cares about, reminding him of what he once had in comparison to that which he still has, that belief really comes back into Mal’s life, a belief that systems like the Alliance, those that want to “make people better”, need to be fought back against. “Someone needs to speak for these people” is what Mal says in reference to the dead on Miranda, and that’s something to believe in.
Mal is placed firmly against the Operative. Mal starts out with nothing and then gains belief by the conclusion of the story: the Operative has an intense, unrelenting belief in the higher power of the Alliance and “better worlds” at the beginning, and then has it all stripped away by the conclusion, with the Operative left a husk by the time the credits role, a man without a purpose, just as Mal was. Indeed, the deleted scene at the end, wherein the Operative asks Mal how he survived after Serenity Valley, is an effective coda to that idea: Mal’s blunt answer, that the Operative never will find out if he keeps standing next to the engine, is the perfect way of telling him to just go and live, and find something else to believe in.
What about River? Her fractured mental state makes any examination of her belief system inherently dodgy, but, in combination with her brother, we might see a bit of simple belief in the power of others. Simon and River are dependent almost entirely on Serenity’s charity and the goodwill of its captain: while Mal talks about giving this up at the beginning, he actively goes out of his way to protect the Tam siblings later on. River needs these people to protect her, so she can find out what it is exactly that has gone wrong in her mind: later she repays the favour, throwing herself into deadly peril in an effort to protect them.
The more minor characters have an array of other beliefs that still make for interesting viewing. Zoe firmly believes in Mal, in a way that he doesn’t even realise: she sees him slipping further away from the person he was during the war, but stays by his side regardless, confident in the belief that this person is still in there, as he is. Wash, on the other hand, has belief in his wife and his marriage as a bedrock. Kaylee’s innate optimism, cheerfulness, and faith in the goodness of people got a lot more play in the TV show than it ever really did in the film, but we could latch onto her belief in a happy ending with Simon maybe, as a powerful driving factor in the way that she carries herself in the final act. Jayne, the film’s ultimate self-indulgent force, at least on Serenity, believes in his own gratification and gain, but has just a smidgeon left over to follow Mal on his run to Miranda, and onto the final climax. And Inara, perhaps she also believes in Mal and the person he has the potential to be, but in different way: as both a prospective romantic partner, and as a more outwardly righteous and just man than she has otherwise encountered thus far.
The battle of beliefs reaches its zenith in the final combat between Mal and the Operative, the right to live as you please versus he right to govern over the governed as you please. On the other side of the complex, Zoe’s belief in Mal must face into a world where such things have cost her her husband: Kaylee faces the possibility of losing any chance of happiness with Simon. Simon, having spent the series believing strongly in the responsibilities of the sibling bond, faces the possibility of losing River, just as she must contemplate losing him. And Jayne, well, Jayne looks deep into the face of his own mortality, a destruction of the self that even someone as seemingly unconcerned as him must quake at a little. But they all come through it: Mal becomes more like the person he used to be, Zoe’s faith in the captain and the ship is reaffirmed, Simon and Kaylee finally get together, Inara takes her place back on the ship with Mal and Jayne, well, Jayne gets to survive another day. The Operative loses his belief and his way.
In the end, Mal has his own belief in something much more simple: love, and the love that can be imparted from crew to ship, that mystical force that “tells you she’s hurt before she keens” and that “makes her a home”. Mal has his belief back, and River joins him, as Serenity sails out, into the black, for further adventures.