Many have heard the child’s song with the words, “this little light of mine, I’m gonna let it shine”. The song encourages children to be a light in a world where darkness can be found in many places. Well, for Christians, the light that we shine is not a little light. It is a light that comes from God. And since God is infinitely powerful, we would do right to consider this light a big light. It is, without a doubt, a light which can completely extinguish darkness wherever it may be found. Consider the following verse:
“And we have the prophetic word more fully confirmed, to which you will do well to pay attention as to a lamp shining in a dark place, until the day dawns and the morning star rises in your hearts, knowing this first of all, that no prophecy of Scripture comes from someone’s own interpretation. For no prophecy was ever produced by the will of man, but men spoke from God as they were carried along by the Holy Spirit.” (2 Peter 1:19–21, ESV)
If the words found in the Bible, are the Word of God, and if God is light, then those words are certainly a light into this world. If there be any darkness in our hearts, let the Word of God be that light that shines in and extinguishes that darkness.
Tim Keller encourages us with the following:
“Second Peter 1:19 says, “And we have the word of the prophets [the Scriptures] … and you will do well to pay attention to it, as to a light shining in a dark place, until the day dawns and the morning star rises in your hearts.” What is Peter saying? He is saying the same thing Paul is saying. Hear this. The world is a dark place, full of unrighteousness and viciousness, the sort of thing that just broke H.G. Wells’ heart, full of distortion and confusion. Nothing is conspicuous; everything is a disaster.
“The Word of God, the revelation, the truth of God, is the only light. The truth of God comes in and says there is hope. There is a God. He created us. He didn’t create us for this kind of condition. We chose to go our own way, so we’ve made a mess of life, but Jesus Christ, the light, has come. If you receive him, that light comes into your life. Eventually the light will come back and take over, and all darkness will be banished forever. You’re supposed to take hold of that hope (the light of God’s truth) and pay attention to it in a world that’s very dark until the morning star rises in your hearts, till the day dawns.” 
The light that the Christian shines is not only the light produced from a loving heart, but it is also a light produced through sharing of God’s Word. This is why it is important for the Christian to share God’s Word with others. God’s Word is that infinitely big light that can extinguish darkness in the lives of others. And the best example of this is through the light of the Gospel where the darkness of sin is forgiven. It is through the pages of Scripture that we learn of Jesus who made it possible for our darkness to be forgiven and forgotten through his loving death on the cross.
1. Timothy J. Keller, The Timothy Keller Sermon Archive (New York City: Redeemer Presbyterian Church, 2013).