The passage
      v16. Here we have one of the best loved verses in the Bible and this because it presents the gospel in a nutshell. In v15 Jesus states that it is necessary for the Son of Man to be crucified so that those "who believe in him may have eternal life." John now reflects on this truth and identifies its cause. God's love for humanity, not just Israel, has prompted the Father to give up his Son to the cross, so that whoever believers in the Son may have life eternal.
      v17. Jesus, in like manner with the gospel, does indeed condemn unbelieving humanity, or more properly, reiterates the condemnation already hanging over them. Yet, this is not the purpose of Jesus' coming; Jesus is sent to save, not to condemn.
      v18. Having stressed that the purpose of Jesus' coming is to save lost humanity, John now underlines the truth that belief in (trust in, reliance on) Christ is the necessary prerequisite for a person to escape condemnation. The person who does not believe confirms their condemnation, and this because they have ignored the salvation offered in God's unique Son.
      v19. The final three verses are difficult to interpret, but there is a clue to their meaning and it lies in the phrase, "this is the verdict." The Bible commentator, Leon Morris, suggests that the "verdict" (judgment, condemnation) is likely referring to the process of judging, rather than the actual judgment. John is explaining how the process of judging works. All humanity stands condemned because of sin, but in Christ's coming that condemnation can be confirmed, or it can be reversed. It all depends on how we respond to Christ, how we respond to the light shining in the world. Condemnation is confirmed on those who love darkness rather than the light, who love darkness because "their deeds were evil." Of course, we all sin, but John is speaking here of habitual sin free from remorse or any desire to know God. Such a person loves darkness and so stands condemned.
      v20. John goes on to explain why "those who do evil" fail to come to the light. His answer is that those who live in habitual evil hate the light because they fear that their evil will be exposed. They are happy in their evil and don't want their cosy world disturbed by the glaring reproof of Christ.
      v21. Thankfully, there are some whose condemnation is lifted. "Those who do truth" ("lives by the truth") come to the light. John uses this phrase to offset "those who do evil." Many commentators suggest that such a person comes to the light because their life is worthy of exposure, but if that was the case John would have used a word like goodness, faithfulness or righteousness. No, although such a person is rightly under condemnation, they seek a way of escape and have discovered it an amazing truth, a truth they now rest on. The gospel proclaims this life-saving truth, a truth John clearly states it in v16. A person who rests on this truth comes to the light and is washed by the grace of God. Before the universe they proclaim that all this is "done through God."

A gospel banner
      Church notice boards and banners can tell us allot about the agenda of a church. There are the "come and join the FULL gospel church" versions which suggest superiority. There is the no message church, other than the service times, usually without notification if cancelled. The "you are unimportant to us" message is emphasized if the notice board is next to unintelligible. There is the embarrassingly dumb and unoriginal, "CH__CH, what's missing?" In Australia a local hotel replied with "P_B, what's missing?" There is the finger-pointing judgmental banner proclaiming that church attenders are going to heaven, but the rest are going to hell. Then there is the gospel, the light shining in the darkness.
      The "light" is the love of God radiating in the person and work of Christ, a life-giving light to a lost and broken world. The gospel message is easily displayed on a church notice board. On commencing my ministry in a particular parish I tried the "Under New Management .... Same Boss" line. Even this little message has a spark of the gospel about it. God lives and loves unconditionally; how simple is that!
      In his gospel, John ponders the impact of God's offer of "everlasting life." In a world facing destruction, there are those who come to the light, who believe in Jesus, who rest on the truth of God's grace in Christ, but there are also many others who hate the light and flee from it. John suggests that those who grip onto their selfish lifestyle do not come to the light because they fear the exposure of their life and thus, the loss of a life apart from God.
      When we banner the gospel, many of those caught up in the push and shove of life will ignore, even flee the light, but some will be attracted to it. So, banner the gospel; something better than "Jesus Saves", given that we don't know what bank he used!

v17
      ou apesteilen (apostellw) "did not send" - did not send away, send forth, commission. Used of an authoritative sending and therefore constantly used of Christian mission, which meaning John obviously wants to convey. God's mission, in the sending of Christ, is not the condemnation of the mankind, but rather salvation.
      iJna + subj. "to [condemn]" - Forming a purpose clause, here negated, God did not send "in order to" condemn.
      krinh (krinw) aor. subj. "condemn" - judge, decide against, condemn. Technically the word is used to offset salvation which is the purpose of Christ's coming. Christ came to save, not to condemn, although a consequence of his coming is the reiteration of the condemnation already hanging over humanity.
      di autou "through him" - The Father does the saving, through the Son.

v18
      kekritai (krinw) perf. "stands condemned" - has been judged. In the "perfect tense the judgment is already past, but the sentence remains", Barrett.
      hdh adv. "already" - already, now after all this waiting. The condemnation of those who do not believe applies in the same way as the justification of those who believe; they have already faced the judgment and are declared lost, condemned, because of their unbelief.
      to onoma (a atoV) "name" - For the ancients, a person's name represents the person. Insult a person's name and you insult the person.

v19
      hJ krisiV (iV ewV) "the verdict" - the judgment, decision. Barrett suggests the word means "condemnation", but Morris thinks that at this point in the passage it means "the process of judging" rather than the sentence of condemnation. It seems better to view the condemnation as applying to all, and that in Christ's coming it is either reaffirmed, or lifted, depending on a person's response to Christ. So, "this is how the process of condemnation takes place, Light has come ........" It of course can be argued that people are condemned on the basis of their morality, or even the sovereign will of God. Barrett says that "when a light shines in a dark night, men who have nothing to be ashamed of make their way to it, seeking illumination; those who are about the deeds of darkness move away from it, lest their deeds should be disclosed." From a Calvinist position we may argue that a person's desire to move toward the light is the consequence of an initial work of the Holy Spirit prompted by the sovereign will of God. Yet, we are best to understand the judgment as a process based wholly on a person's response to Jesus. Those who are ashamed of their sin and want union with the divine will seek the offer of life in Christ, while those who enjoy their life apart from God will flee from the light.
      to fwV "light" - "Light" is an Old Testament image used to describe both wisdom and the law and the prophets. God's revelation is light and its enlightening enlivens; it enlivens because it is good. For John, Jesus is divine life, and this life radiates a pure and good divine truth which gives life.

v20
      oJ faula "evil" - foul, bad, evil.
      iJna + subj. "that" - that [they may not be exposed]. Probably again forming a purpose clause, "in order that they will not be exposed."
      elegcqh/ (elegcw) aor. pas. subj. "exposed" - may be exposed, shown something ....... and therefore "reproved". Used of the Holy Spirit in 16:8 who will "prove the world wrong about...." Barrett suggests "convincing exposure." Morris suggests that "to come to the light means to have one's darkness shown for what it is and to have it rebuked for what it is." The child of the dark does not want their life exposed, while the child of the light does, 21b. John is obviously playing off the two ideas, but does not explain exactly what he means, although we know from experience that the sentiment is true. A person under the grace of God is free from guilt and quite willing to have their sin exposed, while a person apart from God denies guilt and fears any exposure.