This is the only place in scripture where the Spirit is spoken of as doing a work in “the world.” Everywhere else He is spoken of as doing His work in and among the believers.

“convict” (NIV) = “reprove” (KJV) = elegcho = to convict, refute, confute, to find fault with, to correct. This word was used in the sense of cross-examining for the purpose of refuting or convincing an opponent, especially in a court of law. An example of the Holy Spirit later doing this is found in (Acts 2:36-37, 1Cor 14:24). Jesus has just referred to the Spirit as the Paraclete, which normally has legal implications of doing things for the defendant. Here, however, the Spirit is working as the prosecutor to bring about the conviction of the world.

Acts 2:36-37  “Therefore let all Israel be assured of this: God has made this Jesus, whom you crucified, both Lord and Christ.”  When the people heard this, they were cut to the heart and said to Peter and the other apostles, “Brothers, what shall we do?”

1 Corinthians 14:24  But if an unbeliever or someone who does not understand comes in while everybody is prophesying, he will be convinced by all that he is a sinner and will be judged by all,

Jesus had already been convicting the world in regard to sin (7:7). As noted by Gore in the previous verse, the Spirit is not merely trying to make up the difference when Christ leaves the earth, but will complete His mission. What Jesus started, the Spirit will finish. Bernard notes that the Paraclete is here spoken of “not as man’s advocate with God (1 John 2:1), but as Christ’s advocate with the world.”

John 7:7  The world cannot hate you, but it hates me because I testify that what it does is evil.

1 John 2:1  My dear children, I write this to you so that you will not sin. But if anybody does sin, we have one who speaks to the Father in our defence—Jesus Christ, the Righteous One.

This ministry of the Spirit is absolutely essential, not merely because the world needs to be convicted, but also because it needs to be convinced. The world has already regarded Jesus as a sinner (9:24) and itself as being righteous (Luke 18:9) and it is on the brink of bringing judgment against the Son of God. It is in great error on all three points and is in need of correction and the Holy Spirit is the One Who will do it.

John 9:24  A second time they summoned the man who had been blind. “Give glory to God,” they said. “We know this man is a sinner.”

Luke 18:9  To some who were confident of their own righteousness and looked down on everybody else, Jesus told this parable: