Our light becomes darkened when we allow the shadows of the valley to hover over us. The cares of this world, the deceitfulness of riches and the pride of life can all darken our perception of truth.
We can’t shine a light that we don’t have. Do you claim to be a Christian? If you do you should be able to shine when everything around you is dark. Can others around you see better because of the light that you bring into their world?