v1: Faith is a proof that we are “born of God. This is consistent with John 3; we must be born again, so that we might believe. Our faith is in Jesus Christ, as revealed in Scripture.

Again, since we are born of God, we love those who also are born of God.

John Piper quotes John Stott; 'the combination of present tense (believes) and perfect tense (has been born) is important. It shows cleary that believing is the consequence, not the cause, of the new birth. Our present, continuing activity  of believing is the result, and therefore, the evidence of our past exprience of new birth by which we became and remain God's children.' (Finally Alive, by John Piper)

v2: Our faith is proved by our love for the brethren, and our obedience to His commands.

v3: We keep His commands, and that is not a burden to us, but a delight, see Ps 40.8. 'soul rest' comes from obedience. See Jer 6.16; obedience is "rest for your souls." Through Christ we enjoy grace that is sufficient; and can rest in diligent and zealous obedience.

v4-5: Victory over the world, especially its influence in our lives, see John 16.33; Heb 12.1-2. Our faith is "in Christ and “of God and therefore it is powerful, it really works in us.

We recognise the antagonism of the world towards God and towards us; doctrinal, moral, even mental, but we can experience God's victory through our faith in Christ.

v6: Jesus Christ came by water, i.e: physical birth (John 3) and by blood, i.e: His death (Lev 1; Num 19). The same Jesus Christ was born and died, again answering the error that separated Him. The Holy Spirit gives testimony to Christ's coming.

v7-8: The three that testify to Christ, the water, the blood, and the Spirit. They are in agreement about the coming of Christ and about His death.

v9-10: The testimony about Jesus Christ the Son of God. “God's testimony is greater than any witness from man, John 5.31-37; 19.34-35. We therefore have confidence, 2.20, 27; 2 Pet 1.16-18.

We recognise also that not all share this testimony; and many deny the truths of Christ.

v11: The consequence of God's mighty work in Christ for us; we have eternal life, and that life is in Christ, for He is the life. Eternal life is found only in Christ, and we boldly make that claim.

v12: The clear distinction; life is found only in Christ; outside of Christ is only death.

v13: John wrote his letter to give assurance, not in ourselves, but in Christ. All who believe have eternal life in Him.

Thus, John's comments about those outside of Christ have to be understood in their context; that his overarching aim is to give assurance of eternal life to those who believe; not to make them think that they might somehow lose their salvation.

v14-15: The assurance of answered prayer. One consequence of our knowing God and abiding in Him is the fact that we can approach God in prayer. We ask according to His will, for he know His will, and He hears us. Such prayer is assured of an answer; we know that we have what we asked.

Where we experience a lack of answers it is because we have not learned to ask according to His will, James 4.2-3.

v16-17: Interceding for the brethren, 1Cor 11.30; Gal 6.1. John makes a distinction between sin leading to death, and sin not leading to death. A Christian has life, and that life cannot be lost. Yet, Christians do sin, and we have a responsibility to pray for each other.

''I don't think John has particular kinds of sins in view, but rather degrees of rootedness and habitual persistence. There is a point of confirmed sinning which may take you over the line of no return and you will be like Esau who sought repentance with tears and could not find it (Heb 12.16-17).' (John Piper, Finally Alive)

v18: See also 3.9; the child of God is safe in God, each one keeps himself (RAV), taking the personal responsibility to walk close with God (Jude 20-21). As a result, he does not continue to sin.

v19: We are delivered from the dominance of the enemy, no longer living his way. Although the whole world is dominated by the enemy, we need not be, for we are children of God. There is a tension here between God's overall sovereignty and the reality and power of the devil (the evil one). We have confidence in God and we take responsibility to pray and read the word.in our fight against the evil one.

v20: We have received discernment from God through Jesus Christ. We have begun to see truth as distinct from error, so that we might know the truth.

v21: John's closing comment, to keep from idols. He speaks, not just of a man-made object, but of anything that keeps us from worshipping the true Christ.