Commentators unanimously agree that the central point of this verse is the absurdity of hiding a light. Jesus uses the simple, common-sense image of a lamp in a one-room house to illustrate a profound spiritual truth: God gives you faith and grace with the intention that it be visible. Just as a lamp's purpose is to illuminate a room, a believer's purpose is to shine brightly and dispel the darkness of sin and ignorance in the world.