The entire concept of Absurdism is the divorce between man and reality.
In other words, choosing to exist in a universe that is indifferent to you, while knowing this.
The protagonist in The Stranger is brutally honest, and so he his referred to as 'Monsieur Anti-Christ' because he didn't cry at his own mother's funeral, and is not necessarily indifferent, but fairly blunt about how, when speaking to the caretaker and smoking cigarettes at the viewing alongside his mother's friends, he didn't show any emotion other than being tired.
When he's in prison, he points out he could've been in a tree trunk and eventually he would have gotten used to it. What's really absurd is how his character is judged on the merit of how he reacted to his mother's death, more so than how he killed the arab on the beach who was following Raymond. Or even how he fired three extra shots at the corpse, even though he was already dead. The dog and pony act of the court system is almost satirical. Camus asserted in both Reflections of the Guillotine how his earliest memory of his father was him coming back from a public execution and vomiting, and in The Plague, through the character Tarrou, how he became indifferent from his own father and exercised a staunch opposition against the death penalty.
His death at the end of the novel through execution is meant to be taken as a satire on the death penalty, reflecting Camus own views on the subject. Something to consider when reading any Absurdist work, whether Dostoevsky, Kafka, or Camus, is that it's going to be a critique on the society of the time, and the policies perpetuated through the society as a whole.