Conviction about sin
In particular, the Spirit will help the disciples in the work of making known the good news of Jesus. The saying here is a continuation of what Jesus has just said to them about the Spirit testifying about him, through the witness of the disciples (15:26-27). His work will be to “convict the world” (8). The meaning of the word convict is indicated in 3:20, where the sense is of deeds being exposed.
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So “the Spirit of truth” (14:17; 15:26; 16:13) will expose the wrong thinking of people in three particular regards; sin, righteousness and judgement. At the same time he will show people the true meaning of each of these (9-11).
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Firstly, he will bring conviction of sin (9). The basic meaning of sin is that people don't believe the revelation that God has given in Jesus (1:11; 3:19; 15:22). “The world hates me,” said Jesus, “because I testify that what it does is evil” (7). The Spirit will continue to bring people to a response for or against Jesus, with the intention that they will recognise their sin. The Spirit – like Jesus – graciously does this because they don’t believe in Jesus or see their need of him. Conviction about sin is the starting point for receiving him and coming to know him.