(This post contains spoilers. Go watch "Frozen" before you read it)
First, a disclaimer: "Frozen" is not an explicitly "Christian movie", like, for example, "The Passion of the Christ" is. The creators didn't sit down and say "hey, let's make a movie that tells the story of the Christian Gospel". It doesn't make any definite statements about God or Jesus or salvation. Like other great works of art, it can be - and has been - interpreted in many different ways, ranging from insightful to ridiculous, and it has different meaning for different people. You don't have to see it with a Christian interpretation. But if you would like to look into this deeper layer of meaning, it's there, infused throughout the whole story. "Frozen" is the story of perfect love casting out fear. It is a telling of the Gospel story, told like this:
(I'm taking a page out of the "Frozen" book "A Sister More Like Me", and using different colors to tell different parts of the story. Paragraphs in blue describe the movie, and they're in red when they talk about the Gospel in real life.)
Princess Elsa was born with an awesome power - her ability to generate snow and ice. It is part of who she is, part of her birthright. It's a beautiful and powerful ability. But precisely for these same reasons, it's also dangerous, capable of causing disasters.
We are Elsa. Like her, humanity was created to be awesome - made in the image of God and meant to grow to become like him. This is our amazing destiny. But precisely because of our incredible potential, we can also fall into sin, with devastating consequences.
After Elsa accidentally harms her sister Anna, she's given some rules to rein in her powers: conceal it, don't feel it, don't let it show. Limit her contact with people and keep her powers hidden. Here's the thing about these rules: they're severe, but if Elsa actually follows them, they really will keep Elsa and everyone around her safe from her powers. Elsa just has to follow them perfectly.
Like with Elsa, humanity was given God's law to teach us what he wants from us: have no other gods before God, honor your parents, do not steal, love your neighbor as yourself, etc. If we just followed the law, we could theoretically be righteous before God, completely freed from sin, and live perfect lives in perfect societies. We just have to follow them perfectly.
Of course, Elsa can't follow these rules perfectly. It's too much for her to hold everything in. To add to the tragedy, she comes to rely on the rules as her only way to deal with her powers. But they were never meant as a permanent solution; they were only supposed to guide her until she could control her powers. Further adding to her misery, she's warped these rules to "conceal, don't feel. Don't let them in, don't let them see, be the good girl you always have to be", leading her to fear making "one wrong move", because then "everyone will know".
Humanity has Elsa's same problem: we can't follow the law perfectly. No one is good enough to meet God's standards. To add to the tragedy, we have come to rely on the law as our only definition of what it means to be a good person, although the law was never meant to and never could make anyone righteous. Further adding to our misery, we've warped the law into a way to work up our own self-righteousness. This leads us to be judgemental hypocrites, constantly in fear of others discovering that we're not the good boy or girl that we always pretend to be.
So in Elsa's attempt to follow the rules, she utterly fails. The harder she tries the worse her fears and failures become. Her fears cause her powers to go completely out of control during her coronation, and all that she's tried so hard for comes to naught. Her kingdom is enveloped in a sudden winter, and she is cut off from Anna: her only sister and family, and the only person she has a real relationship with.
Humanity's attempt to follow the law also utterly fails. The harder we try, the more clearly we see that sin infects our whole nature and separates us from God. For all that humanity has accomplished, our kingdoms and civilizations are still steeped in sin, and these will all perish with the passage of infinite time. Critically, sin cuts us off from God himself: our only father, and the source of all love and goodness.
Elsa's problem is not something that she can fix herself; she cannot simply try harder, or follow her rules better. She's trapped in a wretched, evil condition that's beyond her ability to control. She says so herself multiple times, in some of the most tragic lines in the film. She sings, "Couldn't keep it in / Heaven knows I tried", and "I'm such a fool, I can't be free / No escape from the storm inside of me / I can't control the curse". She also says, "Don't you see? I can't." when Hans asks her to stop the winter.
Our problem with sin is also not something that we can fix ourselves; we cannot simply try harder, or follow the law more closely. We're trapped in a wretched, evil condition that's beyond our ability to control. Apostle Paul expressed this clearly when he says "I do not understand my own actions. For I do not do what I want, but I do the very thing I hate... I have the desire to do what is right, but not the ability to carry it out" - words that could have easily been Elsa's.
Anna, however, loves her sister and will not let Elsa stay in her "kingdom of isolation", even if Elsa herself has abandoned Anna and Arendelle, and given up on "that perfect girl". Anna pursues Elsa to her castle in the North Mountain to bring her back. But in the ultimate expression of Elsa's fear and lack of control, while screaming out "I can't!", Elsa strikes Anna in the heart with her power.
Anna is the Christ-figure. Jesus loves us and will not let us remain in sin, even if we have already turned our backs on him and lost sight of our divine destiny. He pursued us down this world to bring us back to him, coming to us as a man, as one of us. But in the ultimate expression of our sin, in our ignorance and pride, we crucified and killed the Christ, the very Son of God.
When Anna then insists that things could still be set right, Elsa desperately asks, "How? What power do you have to stop this winter? To stop me?" But Anna actually does have that power, the only power that can save Elsa. For there was always a way for Elsa to control her powers, apart from following the rules: by experiencing an act of true love. In fact, Elsa freezing Anna's heart is precisely what allows Anna to perform this act of love.
We also are in desperate straits. There is nothing we can do to escape our sins. As Apostle Paul says, "Wretched man that I am! Who will deliver me from this body of death?" But what is impossible with humans is possible with God. For there was always a way for us to be good before God, apart from the law: through Christ's love. In fact, the very catastrophe that was the crucifixion is precisely what allows Christ to demonstrate his love for us.
What is love? As Olaf says, it's putting someone else's needs before your own. So in the climax, Anna, in her weakness and frailty, displays the kind of love that can keep loving Elsa even after Elsa strikes her in the heart. She chooses to sacrifice herself and freezes to solid ice, to save her sister's life.
What is love? As it is written, "Greater love has no on than this: to lay down one's life for one's friends". So at the cross, Jesus displays the unconditional love that continued to love his sinful enemies even while we crucified him. He took on all our sins and their consequences, sacrificing himself and saving us.
If, after all this, Anna remained frozen, all hope would have been lost for Elsa. She would have remained trapped in her fear and her kingdom would have been doomed to an eternal winter. But the deep truth in the "Frozen" universe is that an act of true love will thaw a frozen heart. So Anna sacrifices herself, but she's then thawed and restored. By this act Anna and Elsa's relationship is repaired, and Elsa finally becomes the "perfect girl" that she never even dared to dreamed of: freed from her fears, beloved queen of her kingdom, in full control of her powers, and truly sisters with Anna.
Likewise, if Jesus had remained dead, we would have no hope. We would have remained in our sinful condition, and we and all our achievements would have been doomed to perish. But because Jesus humbled himself even to his death on the cross, God raised him from the dead. So Jesus was crucified, dead, and buried, but on the third day he rose again from the dead. Through Christ's death and resurrection, we are restored to God; we are fully freed from our sins and fears, adopted as his children, heirs to his incomparable riches, and truly members of the family of God. That is the story of "Frozen". As you may be able to tell at this point, I was somewhat facetious when I said that "Frozen" is not a "Christian movie". It's true that its makers didn't sit down and say "hey, let's tell the story of the Christian Gospel". They merely told the truth that underlies the whole universe, like all art is supposed to do. But in doing so - in expressing this truth well - they managed to tell the one and only story in the whole universe. So "Frozen" is in fact a Christian movie - in the sense that all good movies are. After all, there is only one story in the universe.
You may next want to read:
The Gospel: the central message of Christianity
An analysis of "Let It Go" in Disney's "Frozen"
The Gospel according to Disney's "Tangled"
Another post, from the table of contents