The bunker operates as an oasis because it represents a reminder of what "home" used to be like. There is a stocked pantry and a place for the man and boy to clean themselves off and feel as if they are at "home." The grace that the boy offers, the father's reminder to him about manners, and the food they eat are ways in which the bunker is an oasis. It is a place that enables some semblance of normalcy to be evident in the lives of both father and son. For both of them, this oasis is temporary because if they remain settled in the bunker, they will be discovered.
In this light, the temporary condition of the bunker can be seen as a lie. The bunker gives a sense of security to the man and the boy, but it is temporary. It is not lasting. The father knows this. When the boy asks if they can stay there, the father recognizes that if they do, they will be discovered. If both of them embrace the lie, they will face death. The only hope for them is to keep moving. In this regard, the bunker can be seen as offering nothing more than a temporary respite. The idea of "home" as seen in the bunker is a lie because of its contingent condition.