The correct answer to this open question is the following.
Is Winthrop's "city on a hill" argument an appropriate metaphor for the American nation?
It makes sense. What John Winthrop meant with this metaphor was that the eyes of other people would be following closely the Puritan´s actions in the Massachusetts Bay Colony. So that served as a motivation for all the Puritans to set the perfect example of how to conduct their lives under strict religious teachings.
The strength of this kind of metaphor is that it provides an illustrative example of the way Puritans lived their lives and felt responsible to set the example for all the people to see them. The weakness of such metaphors is that sometimes people interpret the meaning according to their own beliefs and circumstances.
John Winthrop was the first governor of the Massachusetts Bay Colony. They founded the first town in the region and named it Salem. These Puritans were very strict in their conduct and professed utmost respect for their religious beliefs. Government and church were one of the same. There was no differentiation between one or the other.