Nijay Gupta has posted (19th April 2013) a good quote by Craig Koester about the meaning of “truth” in John’s Gospel. Here I cite that same quote, as well what Koester has to say about the Spirit of truth.
“The Advocate is also called the ‘Spirit of truth,’ a title that binds the Spirit to Jesus and his Father (14:17; 15:26; 16:13). According to John’s Gospel, God is true, and his word is truth, and Jesus bore witness to the truth he received from God (7:18; 8:26, 40; 17:17). By embodying God’s Word, Jesus also embodies God’s truth and can say, ‘I am the way, and the truth, and the life’ (14:6). To say that the Spirit is ‘of truth’ means that the Spirit conveys God’s truth as revealed in Christ. It is how the Spirit engages with the world. In John’s Gospel, truth is not a timeless ideal that is reached by contemplation. It is a power that counters the enslaving dominion of falsehood. Truth is communicated in order to free people from bondage to sin (8:32), to awaken authentic worship of God (4:23-24), and to shape actions that are truly life-giving (3:21).” (Emphasis added)
Jesus is the way, the truth and the life precisely because he (that is, “the Word” in John 1, who made his dwelling among humans) embodies God’s truth. He is not an abstract truth. Nor can we have a relationship with God through an intellectual understanding of the abstract truths about Jesus. Rather, it is through the Spirit of truth that we may know God, who has revealed himself through Jesus.