For all the emotion that people typically associate with the death of a parent, Meursault is nonchalant. The event seems to have no effect on him: "It occurred to me that somehow I’d got through another Sunday, that Mother now was buried, and tomorrow I’d be back to work as usual. Really, nothing in my life had changed" (Camus, pg. 30). What is most discomforting to the reader about the narrator’s attitude is the apparent lack of any motivating source of his indifference. There is not much in the way of back story in for any of the characters. The First part of the novel is a day to day account of a matter of a few days until he shoots the Arab, and then the second half is an overall collection of moments from throughout the trial. There is simply not any room in the book for any explanations for why the character was the way that he was. This was the point, though.
As noted, the murder of the Arab is the breaking point in the story. Again, there really is nothing in the story to prepare us for Meursault to take such as action or any strong and compelling reasoning why it happened. The murder was absurd itself: "It struck me that all I had to do was to turn, walk away, and think no more about it. But the whole beach, pulsing with heat, was pressing on my back perhaps because of the shadow on his face, he seemed to be grinning at me" (74-75). As he stated, the entire murder could have been avoided by simply walking away. The Arab wasn’t threatening him directly, and the shadow forming a grin on the Arab’s face sounded like he was coming up for excuses for what he was going to do, regardless of whether there was any sort of reason for it.
What is most disturbing to the people in the trial is Meursault’s lack of regard for what everybody else calls morality. Camus, in "The Myth of Sisyphus," states that "All systems of morality are based on the idea that an action has consequences that legitimize or cancel it" (pg. 50). To Meursault, actions don’t have any consequences, and this is why they felt that he had to be put to death. He was a complete affront to everything that they considered to make the modern world work, and his existence was a challenge to basically everything that they thought.
Just as the first half ends with a specific event, the second half closes with a specific event, Meursault confronting the priest. The priest should be taken to be symbolic and representative of morality. As a priest, he is a person that people turn to when they need guidance for issues dealing with morality. When the priest continues to insist that he is going to pray for Meursault, he loses control of himself: "Then, I don’t know how it was, but something seemed to break inside me, and I started yelling at the top of my voice. I hurled insults at him, I told him not to waste his rotten prayers on me" (pg. 151). While the death of his mother evoked no response out of him, a priest telling him that he was going to pray for him did. Perhaps this was because Meursault viewed this as an attempt to instill in him the meaning that everybody else viewed as necessary. The death of his mother had no effect on him, and Meursault viewed it as an insult to try, before he died, to attempt to make him into a person that was just like everybody else.