As the light of the world, Jesus promises to give to sinners who follow Him a light that is life, that is, spiritual life, life with God, eternal life. We see this relation between light and life in creation. Without light, plants die. That is why prior to creating the plants in the week of creation, God Himself, first of all, put light in His universe. So it is with man, the sinner.
Man sits in the darkness of sin and death by nature.
He has no spiritual light, and therefore no spiritual life. But Jesus comes as the light of the world to give life to lightless and lifeless sinners. He is the source of life because He is the divine Savior, with power to bestow the light of eternal life to dead sinners such as you and me. Having established what this means that Jesus is the light of the world, we must now say something about the twofold effect which the light of the world has on men. We begin by saying that Jesus is the saving light to the elect people given Him by His Father.