What is the key issue taken up & message conveyed in The Boy in the Striped Pajamas?

The film The Boy in the Striped
Pajamas is adapted from John Boyne's novel by the same name.  Both film and
novel are haunting in their depiction of the Nazis' treatment of the Jews.  What is
particularly disturbing about this story is that it focuses on the children.  One child,
Bruno, is the son of a commandant in charge of a concentration camp; the other child,
Shmuel, is a Jewish boy imprisoned in the camp.  What separates the two children is a
fence.  The fence, established by the Nazis, is what keeps the two children from being
equals and from playing together, but is does not prevent their friendship from
developing.  When Bruno slips under the fence to be with his friend Shmuel and
ultimately faces the same fate as the Jews in the camp, we realize, as does Bruno's
mother, the absurdity of separating children by race or religion, the horror of
attempting to eliminate innocent children, and the danger that all children face in such
an evil environment.