I think that trust in one another becomes a major reason why the boy and his father are able to endure and survive in the difficult conditions of a post- apocalyptic world in which they live and sojourn. It becomes evident throughout their struggles that the only driving force that galvanizes them to continue is trust in one another. We can see this in an exchange when the father defends his son:
You wanted to know what the bad guys looked like. Now you know. It may happen again. My job is to take care of you. I was appointed to do that by God. I will kill anyone who touches you. Do you understand?
He sat there cowled in the blanket. After a while he looked up. Are we still the good guys? he said.
Yes. We’re still the good guys.
Consider the implications of this passage and exchange. The fact that the father and son trust one another in being "the good guys" in a setting where there are few is one reason trust enables them to survive. At the same time, I think that it is trust that compels the son to believe in the father and the father to defend his son by any means necessary. When the father says, "I will kill anyone who touches you," it is an instant where trust is felt and experienced by both the father who recognizes the importance of the bond between both and the son who understands how much the father trusts him and their relationship amidst a world that has severed as many bonds of trust as possible.