All the Light We Cannot See is an anti-war novel that encourages the reader to understand the human side of prolonged military conflicts. Although the novel takes place during World War II, the points that the author raises about the personal connections that transcend politics are also applicable to understanding the effects of war in different time periods and places. One important message the reader can take away is the value of human rights. Anthony Doerr promotes the ideals of equality among people, which transcend nationality, and the harmful consequences of disregarding those values.

The many negative effects of war are emphasized throughout the novel. Doerr does not glorify the heroics of noble causes or patriotism. Instead, the severe hardships that war imposes on innocent non-combatants are explored, as the author includes passages that describe the effects of bombing civilian targets. In particular, Doerr shows the devastating effects on children who have no involvement in deciding the policies that affect them. This loss of control, however, extends to adults. Rather than condemn a character such as Werner, for example, for his involvement in the German military, the author reminds us that he had limited options for avoiding military service. Nevertheless, Werner is responsible for acting according to his conscience: he must make his own decisions about individual actions he is willing to take.

One can also take away the lesson that war can have positive effects in the sense that survival also depends on community and commitment. The characters of Marie-Laure, who is blind, and Etienne, who was traumatized by the previous war, are presented as two individuals who transcend their physical or psychological limitations. Both become important, complementary parts of the resistance movement. While each of them alone likely would have had limited effect, their combined efforts—along with those of many others—make a difference and benefit their compatriots.