During the time of the prophet Jeremiah, Israelites were literal strangers and aliens in a foreign country. Because they had been unfaithful to God, He sent them away from Israel and caused them to be exiled refugees in Babylon. The prophet Jeremiah wrote the exiles a letter from Jerusalem. The letter answered Schaeffer’s question of how those Israelites should live while they were in that strange land. Jeremiah's letter quoted the exact words God had told Jeremiah to say.
First, Peter reminded them of who they were:
1 Peter 2:9a
1 Peter 2:9b