Jesus told his disciples that they are to be the salt of the earth and lamps on a lampstand. Thus, we are called to bring the light of Christ to everyone around us that is struggling with darkness, or to allow others to shine their light on us if we are in darkness.
Matthew 5:13-16
Jesus said to his disciples, ‘You are the salt of the earth; but if salt has lost its taste, how can its saltiness be restored? It is no longer good for anything, but is thrown out and trampled under foot.
‘You are the light of the world. A city built on a hill cannot be hidden. No one after lighting a lamp puts it under the bushel basket, but on the lampstand, and it gives light to all in the house. In the same way, let your light shine before others, so that they may see your good works and give glory to your Father in heaven.
(New Revised Standard Version Bible: Anglicized Edition, copyright © 1989, 1995 National Council of the Churches of Christ in the United States of America. Used by permission. All rights reserved worldwide. http://nrsvbibles.org)