In John 12:47-48 Jesus declares,
"If anyone hears my words and does not keep them, I do not judge him; for I did not come to judge the world but to save the world. The one who rejects me and does not receive my words has a judge; the word that I have spoken will judge him on the last day."
These verses prove conclusively that those who do not keep Christ's words are still a part of the "world" that Christ came to save (for the "world" of which Christ is here speaking unquestionably constitutes the same group of people in both cases – i.e., the human race). But when will the world be saved? Answer: on the "last day."
There can be no doubt that the expression "the last day" refers to the last day of Christ’s reign, when the resurrection of the dead is to take place (John 6:39; 11:24; cf. 1 Cor 15:22-28). According to John 6:39, to be raised up by Jesus on the "last day" is the common blessing of all who have been given to Christ since his resurrection. Prior to his death and resurrection, it is evident that Jesus possessed an awareness that all people had been given to him by God (see John 3:35; 13:3; Matthew 11:27; Luke 10:22) and that God had given him authority over "all flesh" (John 17:2) – a phrase which, in this context, undoubtedly expresses the entirety of the human race (see Numbers 16:22; Psalm 136:25; Jeremiah 32:27; Isaiah 40:5-6; 1 Pet 2:24).
This need not mean that, during his earthly ministry, all people had been given to Christ at that time in a fully realized sense, for Christ had not yet been raised from the dead and received "all authority in heaven and on earth" from his Father. Prior to his resurrection and ascension, it seems that only his disciples had been given to Christ by the Father (John 17:6-9). But because of the certainty of its being realized after his death and resurrection, Christ could consider himself to have already received all people as his inheritance and possession, and to already be Lord of the living and dead (even though, as already noted, Paul says the end to which Christ died and rose again was that he might receive this exalted status from God).
What we're told in the Gospels of Christ being given all people by God is consistent with Psalm 2:8, where we read that, by request, God would give his Son the heathen for his inheritance, and the uttermost parts of the earth for his possession. Similarly, in Hebrews 1:2, we learn that God has appointed his Son "the heir of all (pas)," which necessarily includes all human beings. And because all people are going to be raised from the dead by Jesus, it must be true that this very same all-inclusive group has been given to Christ by the Father. For Jesus declared in John 6:39, "And this is the will of him who sent me, that I should lose nothing of all that he has given me, but raise it up on the last day."
Thus, if one tries to limit the number of those whom the Father has given Jesus to be raised by him on the "last day" to only those who believe on him before they die, it follows that only believers will be raised from the dead by Christ (for nothing is said about a second "last day" in which people are to be raised up by Christ). But if Christ has only believers in view, then it would exclude from the resurrection not only those who have heard the true gospel and made an "informed" decision to reject it, but all infants/young children, mentally disabled people, and all the people throughout history who have lived and died without having ever heard about Christ. Some may argue that these people will be raised by Christ on the last day because of God’s grace alone. But God’s grace is the only reason why any person is given to Christ to be raised (for no one could possibly do anything to deserve or merit such a blessing).
What then does Christ mean by some people being "judged" at this time? It should be noted that nowhere is it said or implied that this judgment will result in either endless or limited punishment, and it would be question-begging to simply assert this to be the case. The word translated as "judge" is krino (the word root of which means "to separate"). The most basic and primitive meaning of krino is "to distinguish" or "discern." However, it is used in a variety of ways in the New Testament, and the exact meaning can only be determined by the context. In this context I submit that the word means "to deem or pronounce someone right or wrong."
But what does Christ mean by saying that he did not come to judge the world but to save the world? Jesus cannot mean by this that he was never going to judge people, for that would contradict other texts both in the Old and New Testament that clearly speak of him judging the inhabitants of the earth by administering rewards and punishments according to their works. How then do we reconcile Jesus’ words here with other texts that do, in fact, speak of Christ judging the world? Answer: Jesus is here speaking of his ultimate purpose for his coming into the world, which is to be manifested to all on the "last day."
Significantly, the "judgment" of which Christ speaks here is to be administered by neither Jesus nor the Father. Instead, it is the "word" (logos) that Jesus had spoken (past tense) which he says will judge them on the last day. But what is meant by this? The "word" evidently denotes all that Christ had spoken in their hearing concerning himself and his purpose for coming into the world. This would include his claim to have been sent by God (vv. 44-45), to be the light of the world (v. 46), and to be the Savior of the world (v. 47). What then does it mean for them to be deemed or pronounced right or wrong by this "word" on the last day? Answer: When they are resurrected by Christ on the last day, the "word" Christ had spoken to them (i.e., his Messianic claims) will be suddenly brought to their remembrance upon their seeing him in his glorified, resurrected body. Like Paul on the road to Damascus, those who rejected him and did not keep or receive his words will at this time realize that they were wrong for not having believed on Jesus as the true Messiah sent by God to save them from their sins.
Thus, when all who rejected Christ's words are saved from sin and death (for Christ said he came to save even those who did not keep his words), the very word that he’d spoken to them concerning his being the Messiah and Savior of the world will judge them to have been mistaken for not believing him when he proclaimed to them the truth during his earthly ministry. The "judgment" of which Christ speaks here concerning those who rejected him as a false messiah will be the direct result of their coming to a realization of the truth, and being convinced that Jesus is indeed the Messiah and Savior of the world. Thus we see that in order for them to be "judged" (i.e., judged to have been in the wrong) by the word Christ spoke to them, they must be saved by him. It is for the very reason that Christ is going to save them from sin and death that they will consequently be "judged" by the word he'd spoken to them (i.e., the word which affirmed the fact that he is the Messiah and Savior of the world, and that his ultimate purpose in coming was to save them). It is this "word" of which they will be reminded on the last day, when they are raised from the dead and caught up to meet the Lord in the air. At this time, all Israel will be saved (Rom 11:26) and will come to the knowledge of the truth of who Jesus is. And being thus brought to this knowledge, and realizing that they were wrong for their past unbelief, they will have no choice but to confess that Jesus is Lord, and to worship him in humble thanksgiving for the grace and mercy shown to them.
"Oh, no single piece of our mental world is to be sealed off from the rest, and there is not a square inch in the whole domain of our human existence over which Christ, who is Sovereign over all, does not cry: 'Mine!'" Abraham Kuyper