Principles
Principles is a key theme we see in this film. It is particularly embodied by Harry as he has ordered Ray to be killed because he's killed a child. Though it was by accident, Harry believes to his core that anyone who kills a child must die. He believes this so much so that he takes his own life when he thinks he's killed a young boy. We also see principles displayed in Ken who protects Ray from Harry's kill order and also doesn't try to stop Harry from killing him for disobeying his order (initially).
Guilt
Guilt is a major theme of this film, and we see it mostly from Ray's character. Ray has completed a hit on a priest in London. But in so doing he's taken the life of an innocent young boy. He is so grieved by this that he's ready to take his own life while in Bruges. He's only stopped by Ken who comforts him in knowing he is a good man that needs a second chance.
Redemption
Ken is the example of redemption outworked in this film. He is the reason that Ray remains alive as he is ordered to kill the younger man but eventually stops him from killing himself. He encourages Ray to understand that he's a good man and deserves a second chance, redemption, for his life - and that will only come from doing good moving forward.
