Order in life is important for everyone. In my everyday life I’ve got a calendar. So I can see when my training begins, when I have to practice and stuff like that. I do some things everyday at the same time (for example practice and training) that’s why I won’t forget anything.
For the public, order in life is also very important. Without it, everywhere would be chaos, for example the road traffic. Just imagine how traffic would be without any rules and traffic lights. Nobody would know when he is allowed to drive. This would be a big problem. Another example is public transport, I think you all know that buses and trains daily arrive at the same time. So everybody knows when the train arrives. These are just two examples, you can see that everyone needs a structured life. In our daily life everything is ordered, if it wasn’t that way we would forget many things, and there would be chaos nearly everywhere.
For our protagonist, Christopher Boone, order in life is more important than for most of us. You can see that in chapter 193, there he structures his morning in little steps. He plans everything and does it exactly that way every morning. For example at 7:20 am he wakes up, at 7:25 am he cleans his teeth and washes his face, at 7:30 am he gives his rat Tobi food and water and at 7:40 am he has his breakfast. And this happens that way everyday. After seeing a yellow car he thinks of the day as a bad day. If he sees a red one, it is a good day for Christopher.
All things considered you can say that a life without order would be horrible for us, but for Christopher it would be like hell. Because he is an atheist, he would not be able to live an unstructured life.