The one who comes from above is above all; the one who is from the earth belongs to the earth, and speaks as one from the earth. The one who comes from heaven is above all. He testifies to what he has seen and heard, but no one accepts his testimony. Whoever has accepted it has certified that God is truthful. For the one whom God has sent speaks the words of God, for God gives the Spirit without limit.
John's testimony about Jesus is this: His life did not begin at conception; he had a former life in heaven. His origin is higher than ours (don't get hung up over heaven being equated with the sky; accept 'heaven' as a ranking metaphor). Being from a 'higher' medium, Jesus has greater knowledge than us who speak only of what we know from experience on earth. More than simply knowing more than us, Jesus doesn't keep silent about what he knows; he speaks the word of God. We who are atheists, do not accept this truth, but some do and to those who accept the words of God receive the Holy Spirit without limit. What we know about the Holy Spirit is that he points to Jesus and sustains our faith in him.