Originally Posted by stephanie
I disagree with your conclusion but think you are right, of course, that it's from that same Biblical theme.
From my perspective, both the Biblical theme (The Chosen People), and American exceptionalism are derived from the same root.
People are born and raised in groups which stand in contrast to other groups with which they compete. The outgroup is always a potential rival or enemy. There are multiple ways of making sure the ingroup is strong and united. Seeing one's own group as being special or different from others, favored by higher powers (god), or carrying a superior mission is part of the bonding and strengthening.
As we culturally evolve towards an ever expanding circle, where "our group" included all peoples, the ways in which groups relate to each other is due to change. There can still be minor rivalries between groups (same as rivalries between towns, or sports teams) but there should be a shared common good.