1 Peter 2:10 “Which in time past were not a people, but are now the people of God: which had not obtained mercy, but now have obtained mercy.”
Paul uses similar wording in Romans. Likely you have been taught that this verse is about some non-Israelite people who have been adopted into the faith of Jesus Christ. This shows that you have not been taught Scripture. You have missed the importance of the phrase “not a people” and have failed to learn who are those people. Scripture teaches a different story than you have been taught. Read Romans 9 and see that the adoption belongs only to Israel. Follow the link back to Hosea to learn who those “not a people” are in history.