Matthew 5:14-16, “You are the light of the world. A city set on a hill cannot be hidden. Nor do people light a lamp and put it under a basket, but on a stand, 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 who is in heaven.”
Here, Jesus was speaking to a crowd, but with these words He was speaking more directly to those who believe in His Word. In these words, therefore, Jesus is also speaking to you and me; and Jesus is also using emphatic language here. If we were to translate it literally from the Greek text, it would be something like, “You yourself are the light of the world.” In the Greek text, Jesus says “you are” twice, hence “you yourself,” which is redundant, and this language is done in Greek (and Hebrew) for emphatic use.
Thus, Jesus says, “You are the light of the world.” You either are or you aren’t; there is no in between. There is no in between light and dark; there is only light and dark. Thus, you either are the light of the world or you aren’t. Jesus uses an image to make His point, which is still helpful for us today. Think of when you light a lamp or a candle in a dark room. When you do, you don’t put a towel or a basket over it, do you? That would defeat the whole purpose of giving light off to the whole room.
Likewise, as a believer in Christ, you are the light of the world. Do not cover it with inaction. Everything that shines has a source of light. On Earth, our source of light is the sun in the daytime and the moon at nighttime, which its light is a reflection of the sun’s light. The sun’s own source of light and heat comes from the nuclear fusion that takes place within its core. Our source of light is Jesus Christ. It is not our own light that shines, for we previously lived in darkness (Ephesians 5:8), but the light of Christ He Himself gives us to shine before others.
How do we let our light we receive from Christ shine before others? Good works, as Jesus says. “But Lutherans don’t believe in good works!” you might say. Yes, we do. In fact, it’s not very Lutheran not to believe in good works. We do not believe in good works insofar as they provide salvation and favour before God (vertical righteousness, i.e. justification by faith), but we do believe in good works insofar as we do them for our neighbour who needs them (horizontal righteousness, i.e. the proper response to our justification by faith).
Therefore, Jesus says, do not neglect good works from your neighbour; let this shine before them so that God your Father might be glorified. As Luther says, “Whatever we do, our teaching and our life ought to shine like a beacon of light to the greater knowledge, honor, and praise of God” (Commentary on Psalm 110, LW 13:295).