"Lighthouses don't fire cannons to call attention to their shining - they just shine."
Dwight L. Moody
Jesus' life here on earth always pointed people to his Heavenly Father, who sent Jesus into the world as a light. In John 12:46 Jesus said, "I have come into the world as a light, so that no one who believes in me should stay in the darkness."
In the same way we who have seen the light and have received Jesus as our saviour are called to be like Him. We are not to conceal our faith, but to shine in this dark world, not to be noticed for who we are or what we do, but rather that others will see the True Light shining in and through us and be drawn to Him. Matthew 5:16 says, "In the same way, let your light shine before men, that they may see your good deeds and praise your Heavenly Father."
The ultimate purpose in being a light in this dark world is that our Heavenly Father be glorified.