N.T. Wright points out that in the ancient world, and even in parts of the modern world, rulers often “set up statues of themselves in prominent places, not so much in their own home territory (where everyone knew who they were and recognized that they were in charge), but in foreign or far-flung dominions… For an emperor, the point of placing an image of yourself in the subject territory was that the subjects in that country would be reminded that you were their ruler, and would conduct themselves accordingly.” (Simply Christian, 37)
While clearly the instinct to set up image-reminders in foreign jurisdictions comes from God himself, the point is worth remembering. People, as icons of the God of heaven, should be constant reminders to us to conduct ourselves according to the justice of the God of heaven. The Trinity has been pleased to fill this world with living pictures, breathing images of himself in order to remind us that he is King of this world.
It’s also worth pointing out that the image of God in people means that on a fundamental level, people are like God. And of course that has been distorted and bent in various ways through sin, but it’s still there all the same. In some sense, every human being should remind us of the Father, Son, and Spirit.