v1-2: God has provided for our sins. Although John has written to encourage us to break with all known sins, God knows our weaknesses, and has made proper provision in Christ, who appears in God's presence for us, Heb 9.24.

The Advocate speaks in our defence, representing the condemned man, so that he may be acquitted. Satan is the accuser of the brethren. The once-for-all sacrifice of Jesus Christ is our propitiation, sufficient for us. And we can add nothing to it. 'Jesus' speaks of the true humanity that He shared, and thus He is able to sympathise with our weaknesses. 'Christ' is the anointed one, who is acceptable before God, speaking on our behalf.

v3-4: Faith demonstrated by obedience; one of John's marks of faith. We cannot claim to know Christ unless we keep His commandments. Many insist that we are not under the law, which is true; but some seek to defend their own disobedience and rebellion, whilst at the same time accusing others of legalism. These Scriptures are clearly directed at such thinking.

v5: We want to know God's love in our lives; obedience to His commands promotes that experience of assurance.

v6: The second "as He." We are not just commanded to avoid sins, but to walk godly, even as Christ did. He is our example and our standard.

v7: John's message was not a new one; the basic call to obedience to God's commands has always existed.

v8: The new command, for Christ has died has risen, and has ascended. There is the new day of grace.

v9-11: Love for the brethren, the next mark of faith. Persistent disobedience blinds the eyes and dulls the conscience.

The first part of the letter, to this point, lays the basis for the deeper teaching about overcoming the wicked one, not loving the world, identifying antichrist, etc. John has laid his foundation of obedience, and he now builds upon that. As in 2 Pet 1.1-4, there is a solid basis for daily Christian living.

v12-14: Growing Christians; perhaps the text of an early hymn;

• little children, young believers; have confidence in the God who forgives, rejoicing in knowing Him;
• fathers, more mature believers; continue in that deeper fellowship with Christ;
• young men, active servants of Christ; be strong in Him, knowing victory by the word of God.

v15-17: Separation from the world. Two vital truths; the world is in opposition to the Father, and the world is passing away. This provides two reasons not to love the world.

James 4.4 insists that we make a decision for God, and make our stand for Him. To do otherwise is described as adultery. We are commanded to do the will of God. By doing so, we understand more clearly the things of the world, and have a clearer perception.

Commenting that the human heart must have an object for its affection, Thomas Chalmers (The expulsion power of a new affection). exposes as error the thought that it is possible simply not to love anything. 'Rather, love for one thing has to be replaced by love for something else.' 

‘Such is the grasping tendency of the human heart, that it must have something to lay hold of…’The ingredients of temptation, as in Gen 3.6; Luke 4.3-9;

• the lust of the flesh, the cravings of sinful man; the appeal to the flesh (Luke 4.3), or good for food;
• the lust of the eyes, the appeal to human reason (Luke 4.9), or good to look at;
• the pride of life, the boasting of what one has and does, the appeal to ambition (Luke 4.6), or good to make one wise.

Thus, worldliness is seen as a matter of attitude rather than specific actions, although worldly attitudes are necessarily manifested in certain actions. Such lusts silence both reason and conscience, and lead to sin, see Hos 4.10-11.

v18: The test of doctrinal truth. It is essential that little children, younger believers, understand doctrine; what is true and what is false, see 4.1-6. It is the "last hour" an indication of the urgency of the time.

Although the antichrist (man of sin, abomination of desolation, beast, 2 Thess 2.3-4) is yet to come in person, his spirit is at work in the world, encouraging lawlessness. This is one indication that it is the last hour.

v19: John comments that "many" had gone out from the fellowship of the believers; for those who promote falsehood cannot tolerate those who love the truth. We see that John refers to religious people. See 1 Cor 11.19; such separation identifies the true believers from the false. The true believer continues in the faith and continues in the fellowship.

v20: Divine anointing, the Holy Spirit, who gives us discernment and understanding. He enables us to see the difference between truth and error, between good and evil. This verse describes a corporate anointing, rather than individual. In the face of false teaching, promoted by the many antichrists, we can be confident in the truth.

v21: Since, therefore, we know the truth, we must continue in it.

v22-23: The test of truth, that Jesus is the Christ; John's test of orthodox belief, see 4.1-6; 5.6-13.

v24: Having known the truth in Christ, it is important that we continue in it.

v25: The encouragement that His promise is eternal life. John writes to give us confidence, reminding us that through faith we have received God's promised salvation.

v26-27: John's written words are consistent with the inner teaching and promptings of the Holy Spirit. By this we can expose those who try to deceive. Some may claim an anointing, but which is counterfeit; by the truth of God's word, and His anointing, we may discern what is false.

v28-29: Christ's return is seen as a motivation to personal holiness. Since He will return for His own, we are commanded to "continue in Him."