"The way, the truth, the life"
The disciples have been slow to realise that Jesus is the way to heaven (4-5) so now he proclaims it clearly to them (6). This is one of the seven “I am” sayings of Jesus recorded in John’s gospel, each of them pointing indirectly to his deity (Exod.3:14; John 8:58-59). Another “I am” saying has a similar meaning: “I am the gate; whoever enters through me will be saved” (10:9). Jesus is not just the one who tells people the way; he himself is the way that leads to God.
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The basis of this is that he is also the truth and the life i.e. all the truth of God and all the life of God are found in Jesus. He came from the Father “full of grace and truth” (1:14,17) so that people might know this truth and this life for themselves (18:37; 10:10).
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In other words, God’s very reality is revealed and occurs in Jesus, which is why he will go on to say, “Anyone who has seen me has seen the Father”, for he and the Father are truly one (14:9-11). There is no one else who can make that claim – hence his emphatic statement that no one can come to the Father except through him (6; Matt.7:14; Acts 4:12). Only the one who has come from the Father’s side (1:18) is able to lead us to know the Father, both in this life and the next.