city on a hill; city upon a hill

a highly visible ideal or example of virtue
—If our country can eliminate poverty within our borders, we have the chance to become a city on a hill for the rest of the world.

hide one’s light under a bushel; hide one’s light under a basket

to keep one’s talents or accomplishments a secret
—Don’t hide your light under a bushel! You need to let everybody know about your volunteer work.

During the Sermon on the Mount, Jesus called his followers “the light of the world.” and gave us two related phrases used today:

You are the light of the world. A city located on a hill [city that is set on an hill] cannot be hidden. People do not light a lamp and put it under a basket [under a bushel] but on a lampstand, and it gives light to all in the house. In the same way, let your light shine before people, so that they can see your good deeds and give honor to your Father in heaven. (Matthew 5:14-16)