This story is cyclical, because it demonstrates two families at odds with each other, and while one might win honor for the day, leaving the other dishonored and humiliated, as time goes on the cycle corrects itself and they switch roles. This shows their heroic journey as the participation in a kind of cycle that transcends them, a cycle of building and destroying of self. Samur's story is a foil for the primary depiction of this cycle, the story of Hrafnkel himself.
Instead of dwelling on the religion itself, consider Hrafnkel's religion a symbol. Since at the beginning of the Saga, he is placing his faith in the universe's forces and the order of nature, he is a symbol for faith, because he trusts in the universe. When he is dishonored and removed from his position of authority, he deconstructs that religious point of view and walks away from his beliefs. The story shows this to be part of an important cycle by which his point of view is flexed, broken down, but ultimately strengthened.
In the end, he is restored to honor, by the gods, one might say, and Samur is removed from the honored position that Hrafnkel desires for himself. He becomes a chieftain, which means he serves the community as a political and religious leader. This means he has made his peace with the universe and has found himself back on the top of the life cycle, in his fully flourishing, unafflicted form. This is a depiction of the cycle of fate, and the implication is that Hrafnkel cannot make the universe do what he wants it to do—when he tries, he only fails. But, he must take action correctly to make a better life.
This balance is similar in kind to his overreaction to Einar riding on his horse. The reader can see that Hrafnkel understands the importance of his self, because he feels his spot on the horse is sacred. Einar violated a sacred place, and so he murders Einar. But, think about it this way: the novel suggests that these honor cycles place humans not above or below one another, but next to each other. The variation comes from time and fate positioning humans in specific places at specific times. That could be said to be the theme of the novel, that fate operates thus.
