V.1-21 These verses really explain what the last three verses of John 2 mean. Many people think that if they are “good living” that they have a better chance of reaching heaven. Nicodemus thought so. But he was told that he must be “born again.”
V.12-21 The Lord as it were, turns to the whole world, and gives us the wonderful news of eternal salvation with God through believing in the Lord Jesus Christ.
V.18 Anyone who does not accept the Lord Jesus as their personal Savior is already condemned. John 12:31 shows that the judgment has already been passed. But if a person believes, all is forgiven and that person is saved. A good verse to give to unbelievers.
V.25-34 John the Baptist says things which are very plain. The youngest person could understand these words.
V.35, 36 The John who wrote this gospel (not the Baptist) is thought to have written these words, because John the Baptist didn’t know about Christianity and eternal life.