As some other reviewers have been saying, Hosseini doesn't focus on a couple of main characters like in his previous books, but divided attention across multiple characters. Some people didn't like it and complained that this novel was less emotionally gripping as the previous two, but I guess the advantage was that many more points of view could be explored. And Hosseini is skillful enough with the characterisation that we are still very much invested in each character (at least for me). 
 (Warning: not-quite-spoilers up ahead) 
 Like, Idris and Roshi. We see the power of having a personal encounter/experience and how it could be a motivator or call to action. But once the experience is removed, it quickly becomes distant and removed and its hold on us diminishes. How could we blame Idris? We recognise the same process in ourselves. Ultimately, Timur is the one who provides the most practical help, yet his motive was a narcissistic one. Is helping for the sake of self-glorification that bad after all? What are the implications for how we do 'community service'? 
 Like, Adel and his jihadi dad. Adel was initially innocent, by virtue of his ignorance. After he found out the truth and eventually came to terms with it, was he now considered "bad" or "evil"? In all probability, he's going to grow up and be like his father. Not out of malice or any ill-intent, but merely because of the lack of moral courage. It's disturbing, because this lack of moral courage probably afflicts most of us. 
 As Nabi said, "I have lived a long time, and one thing I have come to see is that one is well served by a degree of both humility and charity when judging the inner workings of another person's heart."