I John 2

I John 2:1:
My little children, these things write I unto you, that you sin not. And if any man sin, we have an advocate with the Father, Jesus Christ the righteous:

John Bunyan

“[I]t is evident that saints neither can nor dare adventure to plead their cause. Alas! the Judge is the almighty and eternal God; the law broken is the holy and perfect rule of God, in itself a consuming fire. The sin is so odious, and a thing so abominable, that it is enough to make all the angels blush to hear it but so much as once mentioned in so holy a place as that is where this great God doth sit to judge. This sin now hangs about the neck of him that hath committed it; yea, it covereth him as doth a mantle. The adversary is bold, cunning, and audacious, and can word a thousand of us into an utter silence in less than half a quarter of an hour. What, then, should the sinner, if he could come there, do at this bar to plead? Nothing; nothing for his own advantage. But now comes in his mercy-he has an Advocate to plead his cause-”If any man sin, we have an Advocate with the Father, Jesus Christ the righteous.”
— - John Bunyan (1628-1688), “The Work of Jesus Christ as an Advocate, Explained,” The Practical Works of John Bunyan, Vol. IV, p. 251

I John 2:2:
2 He is the atoning sacrifice for our sins, and not only for ours but also for the sins of the whole world.

The very fact that Christ suffered for us, and through His suffering became a propitiation for us, proves that we are (by nature) unrighteous, and that we for whom He became a propitiation, must obtain our righteousness solely from God, now that forgiveness for our sins has been secured by Christ’s atonement. By the fact that God forgives our sins (only) through Christ’s propitiation and so justifieth us by faith, He shows how necessary is His righteousness (for all). There is no one whose sins are not forgiven (in Christ).
— Martin Luther, Commentary on Romans (Grand Rapids, MI.: Kregel, 1976), 78

1 John 2:15:
Love not the world, neither the things that are in the world. If any man love the world, the love of the Father is not in him.

Sheila Alewine

It sounds offensive to us to think we must hate our own families. Surely this is not what Jesus meant? The word means to detest, but in context, Jesus is telling us that our love for God must be so deep and abiding and surpassing that our affection for our families looks like hate. To hate is to “love less.” Our love for anyone, even our own mother and father, cannot supersede our love for God.
This has practical implications. Jesus is describing the cost of being a true disciple. If we love God most, then we will follow Him in spite of any persuasion or influence that would hinder us. The love for God that Jesus describes causes us to give up anything and everything that deters our passion for Him.
Our love for God must surpass not only our love for other people, but also for the things of this world. John tells us if we love the world, we do not love the Father (1 John 2:15). Demas, one of Paul’s disciples, deserted the ministry to which he was called, because he loved the world more (2 Timothy 4:10). A surpassing love for God can keep us from trading away an eternity with Him for a few short years of pleasure here on earth. --Sheila Alewine

I John 2:19:
They went out from us, but they were not of us; for if they had been of us, they would have continued with us; but they went out that they might be made manifest, that none of them were of us.

John gives us insight into what is going on in the lives of those who profess to follow Jesus but then turn away from him, depart from his Word and reject his people. When someone departs from the faith never to be recovered it is not that he has lost the salvation that was once possessed. Rather, such a person demonstrates by his departure that, no matter how loudly he professed to belong to the Lord’s redeemed, he did not genuinely possess the salvation that comes through faith in Christ. Though such people might be among us, they are not “of us.” Paul explains how this happens. How a person lives is determined by what he believes. Those who fall away do so because they become devoted to the “teachings of demons.” This does not mean that they get caught up in the occult. Rather, they come to believe notions that originate in hell and are consequently led away from the faith.
--Tom Ascol

I John 2:28:
And now, little children, abide in him, so that when he appears we may have confidence and not shrink from him in shame at his coming.

Rob Brunansky

To live without regard for the return of Christ is a dangerous error. The return of Christ forms the foundation of the fifth test John gives us in 1 John to help us know whether we have eternal life: How do we relate to the coming of our Lord Jesus Christ? John makes it abundantly clear that those who have eternal life, those who truly have believed in Christ for salvation, are those who are prepared for His return and who are living in the light of His return.
We see in verse 28 of 1 John 2 that when He appears, there will be two options of what will occur for people. Those who know Christ and have eternal life will face that day with confidence based on our relationship with Christ. But other people who do not know Him will be put to shame as they fall under His wrath.
This is the test. The key differentiator, between those who have confidence when Christ comes and those who are put to shame away from His grace and mercy, is that those with confidence abide in Him. We are commanded to abide in Christ, and this is how we prepare for the return of Christ.
John follows up with this command by giving three traits of the people of God who are abiding in Christ.
The first characteristic of those abiding in Christ is that they are pursuing righteousness.
Those who belong to Christ, those who have been born of God, those who genuinely hope for the return of Christ, pursue righteousness. This Greek verb in the present tense indicates that something is in process; those abiding in Christ are in the process of doing what is righteous – or being sanctified, which is the process of becoming more holy, becoming more like Christ, or growing in righteousness. So if we are those who are in the process of doing righteousness, that means we are growing more righteous and obedient to Christ.
The second trait of those who are abiding in Christ and prepared for His coming is that they are rejecting rebellion.
No one can serve two masters. We will either hate the one and love the other, or be devoted to the one and despise the other. We cannot serve righteousness and rebellion at the same time. And those who are abiding in Christ are characterized as rejecting rebellion against God. We are either growing in obedience or growing in disobedience; no one is standing still (although some may move slower than others).
The third trait of those abiding in Christ is that they are resisting deceivers.
The world hates God’s truth. Deceivers claim that individuals can have Christ and they can have sin at the same time. They argue that sin is not really that big of a deal, or that people can abide in Christ and abide in sin simultaneously. We are not supposed to let anyone deceive us in this manner. Those who practice sin are of the devil. We resist deceivers by remembering this simple truth: Christ abides in those who abide in Him. And this means that it is impossible that we should be in the process of rebelling against Him and joining hands with the devil. The one who practices righteousness is righteous.
--Rob Brunansky; The Cripplegate; How to Prepare for the End of the World 9.21.23