Just as each individual has a spiritual identity that isn't tied to history, geography, and ethnicity—in fact, that is untouched by these and other material circumstances—so, too, do nations. The Bible lauds the oneself with oneself with God's household: "Behold, how good and how pleasant it is for brethren to dwell together in unity!" Ps. 133:1.
Conversely, how painful and unpleasant it is when this spiritual affiliation is overlooked and national identity is built on a history of mutual distrust and repeated violence.
Take the case of the Israelis and Palestinians. Land disputes have led to contentious relations. And these clashes have, in turn, generated their own momentum. An atrocity committed by one group against another posits a rationale for violent retribution, which justifies another violent reaction from the other party—and on and on it goes for generations.