In very practical terms, this salvation means walking in the light. Jesus is the light of the world (9:5). The one who follows him will not walk in darkness but will have the light of life (8:12b). The one who walks in the day does not stumble because he sees the light of this world (11:9).
"The light is with you for a little longer. Walk while you have the light, so that the darkness may not overtake you. If you walk in the darkness, you do not know where you are going. While you have the light, believe in the light, so that you may become children of light. (12:35-36)
Walking in the Light is a Matter of Choice
Whether or not we allow the light into our lives and follow it is, in John's gospel, a matter of choice. And not everyone is able to summon either the conviction or the courage. Nicodemus shows up two more times in the gospel after his nocturnal visit to Jesus in chapter 3. I imagine him moving through the gospel in shadows, coming into the spotlight just twice more. He shows up in 7:50-52 where he is willing to attract the criticism of other Pharisees by appealing for due process under law. He makes another cameo appearance in 19:38-42 as he and Joseph of Arimathea, a secret disciple of Jesus for fear of the Jews, bury Jesus' body. Nicodemus brings a ridiculous amount (100 pounds) of myrrh and aloes to place around the body. Nicodemus seems to be a figure who represents those who waver between darkness and light, not hostile to Jesus' mission and message, but unable to make an adequate confession about Jesus when put to the test (Koester, 156).
I can only assume that Nicodemus was relying on other light sources besides Jesus as he moved through John's Gospel. But I have learned lately that I cannot rely on human sources of light. The overhead light in my home office has become unreliable. Sometimes it won't turn on at all when I tap the light switch, and other times, it will go on and then off suddenly. When that happens, I think, "Okay, this is a good opportunity for prayer in the darkness." I move from my desk to the prayer chair in the corner, close my eyes in the darkness and begin to pray and then, without warning, the lights come on again. Human light sources are unreliable. But Jesus the light of the world is the true master of light and shadow. And the Gospel of John is a glorious example of chiaroscuro. It focuses light on the person of Jesus, displacing the claims of other sources of illumination. It shines light on the Son of Man, "lifted up so that whoever believes in him may have eternal life." (3:15) It focuses our faith on the depiction of Jesus as the light, the true light, whose radiance must be seen in and through the cross.
Sources consulted
Raymond Brown, The Gospel According to John, 1-XII
Craig Koester, Symbolism in the Gospel of John
Andrew Lincoln, The Gospel According to St. John
Ad-Free & Subscriber Log-In