Here’s another way to put it: You’re here to be light, bringing out the God-colors in the world. God is not a secret to be kept. We’re going public with this, as public as a city on a hill. If I make you light-bearers, you don’t think I’m going to hide you under a bucket, do you? I’m putting you on a light stand. Now that I’ve put you there on a hilltop, on a light stand — shine! Keep open house; be generous with your lives. By opening up to others, you’ll prompt people to open up with God, this generous Father in heaven. [Matthew 5:14-16 (MSG)]
We need to shine. But, how necessary is a lamp in the sunlight? Sharing our belief with other believers is not enough. If we are going to be light-bearers of the Word, we need to be willing to shine in dark places, too. Father in Heaven, guide us as we step out of our comfort zones and into the dark. Help us to shine your light so all can see and come to know you.
Let your light so shine before men, that they may see your good works, and glorify your Father which is in heaven. [Matthew 5:16 (KJV)]
No one lights a lamp and hides it or puts it under a basket. Instead, everyone who lights a lamp puts it on a lamp stand so that those who come in will see its light. [Luke 11:33 (GW)] 
Devotions of the Heart 