These verses are quite amazing. Read them and think about them. There are proof texts in this chapter so that a person can know if they truly are a Christian.
Test 1 - If you believe that Jesus is the Son of God, the one sent by God and the one chosen by God then you are in God's family. You will only understand this when God opens your eyes to see and understand the truth about Jesus (verse 1). You cannot accept this truth while holding on to your sin. You need forgiveness which can only come when you repent (turn) and trust Christ for salvation.
Test 2 - Love for our fellow believer is evidenced in the fact that we love God and do his commandments (verse 2)
Test 3 - People who are born of God (i.e. in God's family) overcome the world. This means that they don't love the pleasures of world or fall under it's spell. Believers live to please God and not the world around them (verse 5,6)
Test 4 - The person who believes in the Son of God has an internal witness in themselves. This is as a result of the Holy Spirit of God indwelling them.
The internal witness teaches you that God has given eternal life and that life is in His Son. He who has the Son has life; he does not have the Son of God does not have life.
How does this match up to your life!