1 John 1:5
This is the message we have heard from him and proclaim to you, that God is light, and in him is no darkness at all.

God is light. This is the message we are to proclaim. For us to really understand what this message means and learn how to proclaim it, we must ask the question: What does light do?

Firstly, light dispels darkness. Imagine walking into a dark room. You could immediately try to pass through it, but you might run into furniture, bump your head on a shelf, or be unable to find the exit. But if you turn on a lamp or light a candle in that dark room, suddenly things are visible. Just a little light, and the darkness is erased. Remember the words of the psalmist: “Your word is a lamp to my feet and a light to my path.” [Psalm 119:105]

If God is light, however, then why does Exodus 20 say that God was in the “thick darkness” and Psalm 18:11 say that the Lord “made darkness his covering”? At first glance, this may confuse us, but note that the darkness is around God, not God himself. This darkness actually saved Moses’ life, as the Lord told Moses in Exodus 33:20 that “you cannot see my face, for man shall not see me and live.” And we should be quick to remember that David rightly said of God: “even the darkness is not dark to you” [Psalm 139:12] God is eternal, unchangeable light.

Secondly, light can also produce warmth. Fire certainly gives off heat, and even a light bulb gets hot to the touch after a short time. And it is only the Lord who can melt the coldest of sinners' hearts, who can convict the complacent, and challenge the defiant. Even the largest block of ice begins to thaw when exposed to heat. This is what God has done for all of his children: taken our sinful, bitter hearts that were dead in sin, and breathed life and warmed us with his love.

Notice that John is telling us that this message of God as light is one that we heard from him. God has made himself known to us as the great Light of the world in Jesus Christ. This is the message we have heard and now proclaim: “The light shines in the darkness and the darkness has not overcome it.” [John 1:5]