Jesus said both "I am the light of the world" (In John 12) and "You are the light of the world" (in Matthew 5). In Matthew 5, after telling his listeners they are the light of the world, he tells them to let their light shine. We believe Jesus tells us to let our lights shine.
There were no floodlights in Jesus' day, and he clearly meant our lights to help light the way, not to blind others. Let your light shine in ways that light the path for others!
