Redemption
It’s right there in the title, after all. As Andy learns all too well, the system under which he is being punished is not invested in his redemption whatsoever, so he must create the circumstances for it himself. Thus, his "redemption" is a spiritual one, in that he manages to escape from wrongful imprisonment, enact revenge on his enemies, and profit enough to move to his dream home in Mexico. He goes from being trapped in Shawshank for a crime he did not commit, to finding the good life and escaping the oppressive structures that have so hurt him and his friends. Not only that, but he provides redemption and escape for his best friend from prison, Red. Red also undergoes a kind of redemption when he is let out on parole. After telling his judges that he thinks regretfully about his crime everyday, they deem him fit to leave the prison, but the ex-con's real redemption does not come until he gets the note from Andy and sets off to find a new life on the Pacific Ocean. Redemption is thus a major theme in the film, epitomized by the character of Andy and his curiously wise and generous attitude.
Hope
Andy is a character who maintains a steady hope throughout his time in prison. His circumstances have not exactly set him up to be a hopeful man—after all, he has been wrongly given two life sentences for a crime he did not commit—but nevertheless he never gives up his sense of determination and hope. While imprisoned, he spreads this hope and good will among his fellow inmates, building up the library and helping them get educations they never received. His dogged pursuit of a better library for the prison represents his hopefulness and his ability to transmit that hope to others. He also possesses a persistent hope of attaining freedom. He hopes to achieve freedom through legal means, but is more than willing to attain freedom on his own terms when the system continues to fail him. Towards the end of the film, just before Andy makes his great escape, Red tells him to give up hope, as it will drive him crazy. Nevertheless, Andy's hope is what drives him out of his imprisonment and leads him to the life he so desires.
Appreciating Freedom
The single most iconic image from The Shawshank Redemption shows Andy, having finally made his way through the tunnel he’s been working on for decades, sliding through the drain pipe into the stream below, running away from the immediate danger, ripping off his shirt and then standing there with arms outstretched and head tilted back looking toward the sky as the rain washes him. He relishes the first taste of unencumbered freedom he has enjoyed in decades and is determined to make the most of it. His response to escaping stands in contrast with the freedom of his fellow inmates such as Brooks and Red who, upon reentering society, become overwhelmed by the prospect of fitting in to a world that left them behind. The film suggests that part of Andy's enlightenment is his ability to savor and embrace his freedom, in spite of all the associations he has made in prison. Even though the prison completely reorients the prisoners' sense of self and purpose, Andy knows that freedom is sweeter than any security prison life might provide.
Identity
The depression that many of the men are said to face when they are released from Shawshank has to do with their senses of identity. We see this clearly represented by the character of Brooks. When he is released and sent to live in a halfway house, Brooks struggles to acclimate to society, and a huge part of what makes his reentry difficult is the fact that he does not know who he is in the real world. He is not used to the ubiquitousness of automobiles after 50 years in prison, and he is no longer a big fish in a small pond. In prison, he was the librarian, an educated and wise elder among the men, but in the real world, he becomes an old man bagging groceries, and it is this shift in identity that leaves him so hopeless and afraid. Red suffers the same crisis of identity when he gets out of jail, landing in the same halfway house with the same job, but is saved from his own suicidal impulse by the promise of living in Mexico with Andy.
Meticulousness
Part of what defines Andy's character is his meticulousness. He is a quiet and disciplined man, much more accomplished and educated than many of the other prisoners, and from early on in his time in prison, he sets to work on various projects to keep him occupied. As Red narrates to us, staying occupied is an absolute essential of prison life, and Andy is never in want of a purpose. He carves chess pieces out of stone and builds up the Shawshank library through sheer persistence. Once he accrues the necessary funds to make the library functional, he begins to help the men pursue their educations, and displays a quiet determination to help spread knowledge and learning among the inmates.
Andy's greatest feat of determination and meticulousness is his digging of an escape tunnel. Without anyone ever realizing it, for the whole time he has been there Andy has been digging a tunnel out of Shawshank, using nothing but a small rock hammer. His quiet persistence is typified by this discreet getaway, and we see that one of the defining characteristics of his character is his hard working and meticulous attention to his goals.
Companionship
Within the sociality of prison life, the men pursue deep and significant friendships with one another. While so much of prison life is defined by violence, bullying, and pain, Red creates a community and network of men who look out for one another and help each other achieve great things. In particular, Red and Andy share a significant bond, and help one another through difficult times in the prison. In this way, they become one another's companions, and their shared company serves as the source of comfort and solace for both of them. Their conversations with each other become the most important parts of the film, and represent the ways that even through deep hardship, the prisoners find intimacy and caring. Their friendship endures even after they have parted ways, and Andy’s letter to Red shows the depth of their mutual affection. The film ends with Red casting off his self destructive impulse to travel to Mexico to be with his dear friend. Thus the film represents friendship and companionship as a worthy alternative to existential despair.
Religion & Spirituality
Andy is himself a kind of messianic character, in that he is generous, giving, and unselfish in his approach to his fellow inmates. While it is unclear if he is a god-fearing man, his actions reflect a deeply-felt sense of ethics that is at times sacrificial and Christ-like in nature. His quiet and personal spirituality is contrasted starkly by the pious, fundamentalist, and deeply hypocritical religiosity of the warden, Norton. Norton is the opposite of Andy in that his religiousness is loudly proclaimed but barely lived. He speaks out against blasphemy and is quick to quote the Bible, but his leadership style is punitive, ruthless, and unforgiving. He rules by force, and expects his subjects to cower before him. At one point, he admires the fact that Andy is reading his Bible in his cell, but the two men clearly have starkly different relationships to the text.
