First Letter of John - Commentary
SUMMARY: A person who had confessed their sin (once only) and been made clean (holy, sinless) of all unrighteousness by the Holy Spirit (pneuma/Breath), entered the Kingdom of Righteousness. Repentance was past. That person lived righteously from that moment forward until the Lord came.
KEY TEXT:“Everyone who has been born of God does not commit sin, because His seed remains in him, and he cannot sin, because he has been born of God.” (1 Jn 3:9)
AUDIENCE: Christians. “I have not written to you because ye know not the truth, but because ye know it” (1 Jn 2:21). All the true believers knew the truth and lived it every day. “And these things write we to you, that your joy may be full.” (1 Jn 1:4) The reason they could have confidence to “ask anything and Him hear” (5:14), was because they were without sin and kept the commandments and knew the truth and remained in fellowship.
PURPOSE: Encouragement and teaching. To highlight what characterises a Christian. To warn what characterises a non-Christian. To show the steps for receiving salvation and repentance once for all.
1Jn 1:1 That which was from the beginning (arche G746), which we have heard, which we have seen with our eyes, which we have closely looked at, and our hands have handled, of the Word of life (zoe G2222).
John declares that he has seen the Messiah himself. The Messiah was with them from the beginning of His ministry among them. “You have been with me from the beginning.” (John 15:27). From that beginning, John heard Jesus teach, watched His presence and actions, and participated in ministry in delivering the Word of Life. Christ is Himself the Word of Life, speaking the Father’s very thoughts and living His will. From that source, Jesus brought the exuberant life which Israel had longed for, for centuries. A life set free from the curse of sin and death. A vital overflowing zestful life grounded in the very heart of God, Yahweh Elohim. From this life which John had received by grace, John lived and ministered.
1Jn 1:2 For the life appeared, and we have seen and testify, and show to you that ages (aionios) life, which was with the Father and that appeared to us.
Jesus was the visible declaration of that zestful life, a life that would exist through that age and ages to come. John had received that life and he wanted others to understand what he had received so they might receive it too. A life free from sin, grounded in their Messiah who had bought them their pardon by his death and resurrection.
1Jn 1:3 That which we have seen and heard declare we to you, that you also may have fellowship/partnership with us: and truly our fellowship is with the Father, and with his Son Jesus Christ.
There are some John is talking to who do not yet have fellowship with them. The ‘we’ are declaring to the ‘you.’ There are 2 sets of people in this sentence. Those who have fellowship currently in the Father and Jesus, and those who don’t yet. John hopes that all the ‘you’ will join with the ‘we’ but they are not there yet.
1Jn 1:4 And these things write we to you, that your joy may be full.
Gradually we learn the composition of John’s audience. At this stage, the some or all of the audience are not full of joy. This is in contrast to John (and the we) who have that joy already.
1Jn 1:5 This then is the message which we have heard of him, and declare to you, that God is light/fire (phos G5457), and in him is no shadow/dimness (scotia G4653) at all.
This light/fire which God manifests, reveals things for what they truly are. There are no half truths. This all empowering light/fire is an important aspect of God that forms the basis of the message of John to his audience.
John now raises 5 conditional (if) points. These characterise who a Christian is in and the process of becoming one, in contrast to one who is not.
1Jn 1:6 If we say that we have fellowship with him, and walk in darkness, we lie, and do not the truth:
It is not possible for John to have partnership with God and walk in half truths at the same time. Either he is in fellowship and has the light and walks blamelessly in righteousness, or he isn't and doesn't. It's one or the other. There is no middle ground and no going to and from one side to the other. If there is any sin or unrighteousness, then he is not in fellowship with Jesus and therefore neither in fellowship with the other believers.
1Jn 1:7 But if we walk in the light, as he is in the light, we have fellowship one with another, and the blood of Jesus Christ his Son cleanses us from all sin.
Walking in the light/fire of God the Father (ie in righteousness) is the basis for fellowship with others who likewise walk like this, whose sins have been cleansed by Messiah Jesus’ blood.
1Jn 1:8 If we say that we have no sin, we deceive ourselves, and the truth is not in us.
If John was to declare that he had no sin, he would be deceiving himself they had all sinned prior to Jesus cleansing it all.
1Jn 1:9 If we confess our sins, he is faithful and just to forgive us our sins, and to cleanse us from all unrighteousness.
To enter full fellowship, John had to confess his sins. Following this God brought John into full fellowship by faithfully forgiving and cleansing him of all sins. John was at that moment in the place of full righteousness – that is, into His fellowship where John then lived in the light, not in half truths. This was a once only pardon (Heb 10:10), for Jesus died once only to pardon all sins (Heb 9:28) for if such a person sinned willfully again there was no more pardon for sin (Heb 10:26.)
1Jn 1:10 If we say that we have not sinned, we make him a liar, and his word is not in us.
John reiterates v8. If John had said he had not sinned, then God’s Word would not have been true nor His Word in him. But John had sinned prior to confession and forgiveness and cleansing.
Until now John has primarily summarised what they had gone through to get into full fellowship with the Father and Son. Having established that the discples are all free of sin, John exhorts them to remain in this position and not to fall back.
1Jn 2:1 My young children (teknion G5040), these things write I to you, that ye sin not. And if someone sins, we have an advocate (parakletos G3875) with the Father, Jesus Christ the righteous:
Jesus called His apostles ‘young children’ (John 13:33) prior to His crucifixion so the phrase refers to those young in the faith not in age. John says that he is writing all these things so that these ‘young children’ do not sin. Not sinning is very important. John adds that “if someone sins.” Since the believers are not committing sin (and can't commit sin), this refers to the rest of the world (v2) for Jesus atoned not only for them but also for others who were yet to come into the kingdom of righteousness. So if someone (else) sinned, the believers (“we have an advocate”) knew that Jesus was there for the sinner's confession. The sinner could therefore come to Christ by asking forgiveness and enter into full fellowship (as in 1 John 1:9.) He doesn’t call the young children sinners for they are not.
1Jn 2:2 And he is the atonement for our sins: and not for ours only, but also for those of the whole world.
Not only did Jesus cleanse all the sins of the believers (we/our) but also anyone else who came to him in repentance and faith. If any in his audience hadn’t received His atonement, they could.
1Jn 2:3 And hereby we do know that we know him, if we keep his commandments.
John knew he knew God because John kept His commandments. If they didn’t keep His commandments, they wouldn’t know Him. Black and white. Keeping the commandments was the sign they were in fellowship.
Jn 2:4 He that says, I know him, and keeps not his commandments, is a liar, and the truth is not in him.
John warns his audience to watch out for false Christians. He states that if someone says they know God but doesn’t keep His commandments, then the truth and the light/fire of God is not with that person. They are living in shadows/darkness.
Keeping His commands is very important. John doesn’t specify which commands but Jesus had said, “If you love me, keep my commandments.” (John 15:15) And there were many and they included the 10 commandments. “If you keep my commandments, you shall abide in My love.” (John 15:10).
So to discover if a person was walking in the light and truth, keeping the commandments was one way to prove it.
1Jn 2:5 But whoso keep his word, in him verily is the love of God completed: hereby we know that we are in him.
John knows that God’s love is complete in them because they do keep His commandments. What a strong wonderful statement to make.
1Jn 2:6 He that says he abides in him ought himself also so to walk around, even as he walked around.
One aspect of living in Jesus is to walk around as Jesus walked around. Walking by His example was necessary.
1Jn 2:7 Brethren, I write no new commandment to you, but an old commandment which you all had from the beginning. The old commandment is the word which ye have heard from the beginning.
John’s audience of believers knew the commandments which Jesus had given at the beginning (2:24) of His ministry.
1Jn 2:8 Again, a new commandment I write to you, which thing is true by him and for your sake: because the darkness is past, and the true light now shines.
John reminds the believers that sin was darkness and that has passed from their lives because Jesus shines in its place. What is the new commandment? He explains it in verses 9-11. The commandment to love their Christian brethren. John 17:26 “so that the love with which You have loved Me may be in them, and I in them.”
1Jn 2:9 He that says he is in the light, and hates (miseo G3404) his brother, is in darkness even until now.
John must be aware of some false Christians who say they are in fellowship with the Father but they are not because they hate their brother. That hater has remained a sinner and not yet moved out of darkness. John warns the Christians to watch out for such people.
1Jn 2:10 He that loves his brother abides in the light, and there is no occasion of stumbling in him.
In contrast, true Christians do love their brothers and don’t trip up at all (in regard to the love command) and so prove that they are in fellowship.
1Jn 2:11 But he that hates his brother is in darkness, and walks in darkness, and knows not where he goes, because that darkness has blinded his eyes.
In contrast again, John reiterates his former point. Hatred blinds a person’s eyes to the direction of his life and his relationships.
1Jn 2:12 I write to you, young children, because your sins are forgiven you for his name's sake.
John turns to the young (in faith) to remind them that their sins were forgiven for Jesus' sake, because He had promised such to those who confessed all their sins.
1Jn 2:13 I write to you, fathers, because ye have known him from the beginning. I write to you, young men, because ye have overcome the wicked one. I write to you, young children, because ye have known the Father.
1Jn 2:14 I have written to you, fathers, because ye have known him that is from the beginning. I have written to you, young men, because you are strong, and the word of God abides in you, and you have overcome the wicked one.
John’s audience of forgiven ones includes all ages and stages of their walk by faith. They know the Father and have overcome Satan and they keep God commands. John returns now to warnings about those who are outside fellowship.
1Jn 2:15 Love not the world, neither the things in the world. If anyone loves the world, the love of the Father is not in him.
Those in fellowship could identify someone who wasn’t in fellowship because they loved society and its trappings. This showed the Father’s love was not with them. There was no middle ground.
1Jn 2:16 For all that is in the world, the coveting of the flesh, and the coveting of the eyes, and the pride of life, is not of the Father, but is of the world.
John itemises the trappings – coveting by the flesh, coveting by the eyes, boasting about their life. These primarily broke the 1st and 10th commandments – “No other gods before me” and “Do not covet anything belonging to your neighbours.” (Exod 20:3, 17) Jesus added: “Whoever looks on a wife to covet her has committed adultery with her already in his heart.” (Math 5:28) David wrote “The wicked boast…” (Psalm 10:3) Those in fellowship know not to boast except for boasting what the Father has done. (Psalm 44:8).
John knows that all these believers obey the 10 commandments including the very thought of the commandment (as Jesus added), and he strongly wants their resolve to remain holy until the Lord returns.
1Jn 2:17 And the world passes away, and the lust thereof: but he that does the will of God abides for ever.
Society will pass by and its trappings and coveting, but a person living and doing God’s commands will still be going in ages to come.
1Jn 2:18 Little children, it is the last/final (eschatos G2078) hour (hora G5610) and as you have heard that antichrist (antichristos G500) shall come, even now are there many antichrists; whereby we know that it is the last hour.
John tells them that the period of time they are in is the closing chapter of the age, proven by the fact that there are so many antichrists in their midst (ie so many denying Jesus the Messiah.) John is convinced the age is about to close. This knowledge gives John the platform for encouraging the true believers to stand fast to the end which some of them would see happen. They knew because Jesus had said to the Apostles, “I have told you before it happens….When you see all these things, know that it is near…. This generation shall not pass until all these things be fulfilled.” (Math 24:25, 33-34)
1Jn 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 that they might be made manifest that they were not all of us.
When the believers repented and received full pardon from all unrighteousness, those who truly had made a life change continued to meet with each other. Those who left the fellowship proved they remained unconverted.
1Jn 2:20 But ye have an unction/anointing from the Holy One, and ye know all things.
Those who remained in fellowship had received an anointing from the Lord which gave them the ability to know all the things they needed to know.
1Jn 2:21 I have not written to you because ye know not the truth, but because ye know it, and that no lie is of the truth.
John confirms that his audience are all believers and that they all know what it true.
1Jn 2:22-23 Who is a liar but he that denies that Jesus is the Christ? He is antichrist, that denies the Father and the Son. Whosoever denies the Son, the same has not the Father: he that acknowledges the Son has the Father also.
The antichrist was anyone who denied that Jesus was the Messiah and that Jesus was the Son of God. These ones were outside the fellowship of believers, just as anyone who hated his brother or committed adultery or didn't fellowship was also outside.
1Jn 2:24 Let that therefore abide in you, which ye have heard from the beginning. If that which ye have heard from the beginning shall remain in you, ye also shall continue in the Son, and in the Father.
John stresses once again that they must continue to keep all the commandments (including to love each other) and by this they will stay in fellowship with the Lord.
1Jn 2:25 And this is the promise that he has promised us, eternal (ages) life.
The reward of remaining in fellowship is life, not just in this age but in ages to come.
1Jn 2:26 These have I written to you concerning them that seduce (lead astray) you.
John wants them to know without a doubt what they believe so that the liars among them may not be able to lead them astray and back into sin.
1Jn 2:27 But the anointing which ye have received of him abides in you, and ye need not that any man teach you: but as the same anointing teaches you of all things, and is truth, and is no lie, and even as it has taught you, ye shall abide in him.
John rejoices that the God has put an anointing inside every true believer so that they know what is true.
1Jn 2:28 And now, little children, abide in him that when he shall appear, we may have confidence, and not be ashamed before him at his coming.
The result of their continuing to live a holy life will give them confidence when Jesus appears. For if they sinned after having received Christ, there would be no way to undo the sin and be forgiven again, and they would be ashamed when Jesus returned.
1Jn 2:29 If ye know that He is righteous, ye know that every one that does righteousness is born of him.
That holy life was dependent on them living righteously every day and so prove to be children of their righteous God.
1Jn 3:1 Behold what manner of love the Father has given us, that we should be called children of God. Therefore the world does not know us, because it did not know Him.
Just as the unrighteous world did not understand who Jesus was, so they didn't understand the believers.
1Jn 3:2 Beloved, now we are children of God, and it has not yet been revealed what we shall be. But we know that when He shall be revealed, we shall be like Him, for we shall see Him as He is.
Just as Jesus was a child of God, so too are they now that they are in Him. John doesn't know what form the believers will take in the age to come except that they will be like Jesus. Indeed they shall see Jesus in his new form.
1Jn 3:3 And everyone who has this hope in him keeps himself pure, even as he is pure.
A believer stays pure because his Lord is pure.
1Jn 3:4 Whoever abides in sin breaks the law, for sin is lawlessness.
It can be seen if someone is sinning because they break the law.
1Jn 3:5 And you know that He was revealed that He might take away our sins, and in Him is no sin.
There is no sin in Jesus, and he took away the sin from the believer at repentance so the believer would live free of sin and its guilt.
1Jn 3:6 Everyone who abides in Him does not sin. Everyone who sins has not seen Him nor known Him.
Having been made free from sin and unrighteous at repentance, the believer abides in Jesus by living a fully righteous sinless life. In contrast, the unbeliever continues in sin proving that they have neither seen Jesus nor known him.
1Jn 3:7 Little children, let no one deceive you. He who does righteousness is righteous, even as He is righteous.
There was only one way to remain righteous and that was to keep doing righteous acts, ie obeying and living the commandments of Christ day by day
1Jn 3:8 He who practices sin is of Diabolos (the accuser), for Diabolos sins from the beginning. For this purpose the Son of God was revealed, that He might undo (luo/loosen) the works of Diabolos.
All who continue to break the law belong to Diabolos (Devil.) Jesus came to break apart the works of evil.
1Jn 3:9 Everyone who has been born of God does not commit sin, because His seed remains in him, and he cannot sin, because he has been born of God.
True believers cannot sin because having cleaned them of all sin, Jesus' very DNA lives inside them.
1Jn 3:10 In this the children of God are revealed, and the children of Diabolos: everyone not practicing righteousness is not of God, also he who does not love his brother.
So it was very apparent who were true believers – if they broke the Law and didn't love their brethren, then they were not children of God. If they kept the law and loved the brethren, then they were children of God.
1Jn 3:11 For this is the message that you have heard from the beginning, that we should love one another;
Jesus had instructed them to love each other.
1Jn 3:12 not as Cain who was of the evil one, and killed his brother. And for what did he kill him? Because his own works were evil, and his brother's things were righteous.
Cain killed his brother proving his life was full of evil. He neither kept the law nor loved his brother.
1Jn 3:13 Do not marvel, my brothers, if the world hates you.
It was not surprising that unrighteous people hated righteous people because their value systems were opposed.
1Jn 3:14-15 We know that we have passed from death to life, because we love the brothers. He who does not love his brother abides in death. Everyone hating his brother is a murderer. And you know that no murderer has everlasting life abiding in him.
Like Jesus (Math 5:21-22), John puts hatred and murder in the same box. A believer would never hate or kill his Christian sibling.
1Jn 3:16-18 By this we have known the love of God, because He laid down His life for us. And we ought to lay down our lives for the brothers. But whoever has this world's goods and sees his brother having need, and shuts up his bowels from him, how does the love of God dwell in him? My children, let us not love in word or in tongue, but in deed and in truth.
Jesus laid down his life for the believers who would come into fellowship with Him. Likewise, believers share their money and resources with other believers (not with unbelievers.) Jesus lay down his life for people who would come to trust him and live righteously. He did not lay down his life for people who would not come to believe and continue to live in sin. Therefore believers were to share their goods with believers not unbelievers.
1Jn 3:19 And in this we shall know that we are of the truth, and shall assure our hearts before Him, 1Jn 3:20 for if our heart accuses us, God is greater than our heart and knows all things.
As believers loved and shared their belongings, they felt assurance and peace before God. Without this confidence their heart would accuse them but God was greater than that and would always reassure the righteous believer.
1Jn 3:21 Beloved, if our heart does not accuse us, we have confidence toward God. 1Jn 3:22 And whatever we ask, we receive from Him, because we keep His commandments and do those things that are pleasing in His sight.
It was important to know the peace of heart and confidence in God as a result of living sinless righteous lives and keeping His commands, because then the believer knew that whatever they asked from the Lord, the Lord gave them. This was another way they knew they were walking in God – all their prayers were answered positively.
1Jn 3:23 And this is His commandment, that we should believe on the name of His Son Jesus Christ, and love one another, as He gave us commandment. 1Jn 3:24 And he who keeps His commandment dwells in Him, and He in him. And by this we know that He abides in us, by the Spirit which He gave to us.
John summarises how they knew they were walking with God – they believed Jesus was the Son of God and the Messiah, they loved all the believers, they kept all His commandments, they knew the Spirit which led them.
1Jn 4:1 Beloved, do not believe every spirit (pneuma/breath), but try the spirits to see if they are of God, because many false prophets (untrue foretellers) have gone out into the world (region.)
Spirits are the breaths of people, who either speak truth or falsehood. False prophets spoke false things. The Holy Spirit (Breath) spoke truth. All the points John has made earlier are signs of what is true and what is not. The believers are to subject what they hear to all the commandments of Christ. John states that there are many false prophets roaming the land and other writers verify this fact.
1Jn 4:2 By this you know the Spirit (pneuma/Breath) of God: every spirit that confesses that Jesus Christ has come in the flesh is of God; 1Jn 4:3 and every spirit that does not confess that Jesus Christ has come in the flesh is not of God. And this is the antichrist you heard is coming, and even now is already in the world.
Believers who confess Jesus came in the flesh were speaking truth. John declares that the antichrist (who denied Jesus the Messiah) was already among them. This is how John knew it was the last hour and the age would close and Jesus return imminently.
1Jn 4:4 You are of God, little children, and you have overcome them, because He who is in you is greater than he who is in the world.
The true believers had overcome falsehood and had Jesus in them who was greater than the antichrist. So they had every reason to be confident knowing Jesus would protect them.
1Jn 4:5 They are of the world, therefore they speak of the world, and the world hears them. 1Jn 4:6 We are of God. He who knows God hears us. The one who is not of God does not hear us. From this we know the spirit of truth and the spirit of error.
Unbelievers lived comfortably in the world of sin and that world listened to the false prophets. In contrast, the believers who lived righteously knew they had God's ear and not the world's.
1Jn 4:7 Beloved, let us love (agape, social/moral love) one another, for love is of God, and everyone who loves has been born of God, and knows God. 1Jn 4:8 The one who does not love has not known God. For God is love.
Believers loved the saints (ie other believers.)
1Jn 4:9 In this the love of God was revealed in us, because God sent His only begotten (monogenes) Son into the world that we might live through Him.
Yahweh sent Jesus into their world to reach those who would live in him.
1Jn 4:10 In this is love, not that we loved God, but that He loved us and sent His Son to be the atonement for our sins. 1Jn 4:11 Beloved, if God so loved us, we ought also to love one another.
The believers' sins had been washed away by Jesus' blood. Jesus gave them a fresh start with a life of purity, free from sin. Able to love each other from the heart.
1Jn 4:12 No one has seen God at any time. If we love one another, God dwells in us, and His love is perfected in us. 1Jn 4:13 By this we know that we dwell in Him, and He in us, because He has given us of His Spirit.
God the Father has never been seen. Yet by love for each other, God's love dwells in the believer. And the clincher is the abiding Spirit/Breath which the believer knows is in them.
1Jn 4:14 And we have seen and testify that the Father sent the Son to be the Savior of the world. 1Jn 4:15 Whoever shall confess that Jesus is the Son of God, God dwells in him and he in God. 1Jn 4:16 And we have known and believed the love that God has in us. God is love, and he who abides in love abides in God, and God in him.
John had seen Jesus in person and knew him to be the Messiah.
1Jn 4:17 In this is our love made perfect, that we may have boldness in the day of judgment, that as He is, so also we are in this world.
John looks to judgment day and knows he will have boldness on that day because he has lived a righteous life following conversion and loves the saints and confesses Jesus is the Messiah and has the Spirit in him.
1Jn 4:18 There is no fear in love, but perfect love casts out fear, because fear has torment. He who fears has not been perfected in love. 1Jn 4:19 We love Him because He first loved us.
John has nothing at all to fear because he has God's perfect love inside him.
1Jn 4:20 If anyone says, I love God, and hates his brother, he is a liar. For if he does not love his brother whom he has seen, how can he love God whom he has not seen? 1Jn 4:21 And we have this commandment from Him, that he who loves God should love his brother also.
1Jn 5:1 Everyone who believes that Jesus is the Christ has been born of God. And everyone who loves Him who begets also loves him who has been born of Him. 1Jn 5:2 By this we know that we love the children of God, whenever we love God and keep His commandments. 1Jn 5:3 For this is the love of God, that we keep His commandments, and His commandments are not burdensome.
John restates the position of the believer – believes Jesus is the Messiah, loves Jesus, loves the children of God (ie other believers), keeps his commandments.
1Jn 5:4 For everything that has been born of God overcomes the world. And this is the victory that overcomes the world, our faith. 1Jn 5:5 Who is he who overcomes the world, but he who believes that Jesus is the Son of God?
The believer overcomes the world by walking in Christ and his commandments and love.
1Jn 5:6 This is He who came through water and blood, Jesus Christ, not by water only, but by the water and blood. And the Spirit is He who bears witness, because the Spirit is the truth.
Jesus was baptised by water and by blood. The Holy Spirit appeared at his water baptism and arrived after his resurrection.
1Jn 5:7 For there are three that bear witness in heaven: the Father, the Word, and the Holy Spirit (Breath), and these three are one.
The Word is Jesus. All three are united in their witness.
1Jn 5:8 And there are three that bear witness on the land: the Spirit (Breath), and the water, and the blood; and these three agree as one.
The Holy Spirit, water baptism and blood shed by Jesus all declare the truth that Jesus is Messiah.
1Jn 5:9 If we receive the witness (marturia/evidence) of men, the witness (evidence) of God is greater. For this is the witness of God which He has testified about His Son.
People may say they believe Jesus is the Messiah but God's evidence holds far more weight.
1Jn 5:10 He who believes on the Son of God has the witness in himself. He who does not believe God has made Him a liar, because he does not believe the record that God gave of His Son. 1Jn 5:11 And this is the record, that God has given to us everlasting life, and this life is in His Son. 1Jn 5:12 He who has the Son has life; he who does not have the Son of God does not have life.
1Jn 5:13 I have written these things to you who believe on the name of the Son of God, that you may know that you have everlasting life, and that you may believe on the name of the Son of God.
John writes to assure the believers that they already have the life that will take them through the ages.
1Jn 5:14 And this is the confidence that we have toward Him, that if we ask anything according to His will, He hears us.
And they know they have this life because everything they ask for in His will, they receive.
1Jn 5:15 And if we know that He hears us, whatever we ask, we know that we have the petitions that we desired of Him.
Because they know all things, they know to only ask for what is in His will.
1Jn 5:16 If anyone sees his brother sin a sin not to death, he shall ask, and He shall give him life for those that do not sin to death. There is a sin to death, I do not say that he shall pray for it. 1Jn 5:17 All unrighteousness is sin, and there is a sin not to death.
John mentions a sin that is not a mortal sin and if a believer does this sin, the other believer will ask the Father and the believer will be granted life. John doesn't tell us what this sin is.
1Jn 5:18 We know that everyone who has been born of God sins not, but the one born of God guards himself, and evil does not touch him. 1Jn 5:19 We know that we are of God, and all the world lies in evil.
John knows that he and his fellow believers do not sin because God is in them and guards them against sin so that evil can't break through. Their world of righteousness is in contrast to the world of evil.
1Jn 5:20 And we know that the Son of God has come, and He has given us an understanding so that we may know Him who is true. And we are in Him that is true, in His Son Jesus Christ. This is the true God, and the everlasting life. 1Jn 5:21 Little children, guard yourselves from idols. Amen.
The believers live in Christ day by day, moment by moment. But they needs to be vigilant at all times as the end draws nigh.
John does not countenance sin in the Christian camp. If anyone is still sinning, then they continue “in darkness and have not come into the light” (2:9). The holy believers are surrounded by people who claim to be Christians but still walk in darkness and have not yet received the anointing. John writes to encourage those who are in the camp to continue on in holiness to the end because the end is near.
John says Christians are believers if they:
have repented and been cleansed of all unrighteousness
know the Holy Spirit who lives in them
know all things.
testify that Jesus is the Messiah and Son of God (Yahweh)
obey and keep all the (10) commandments
love and provide for the needs of other believers
walk in purity and do not sin
watch God answer every prayer they ask in His will
find that the unrighteous world does not listen to them
walk as Jesus walked.
John’s whole letter is to encourage the saints (holy ones) to remain in their holy walk. In 2:15 he contrasts their state with that of the person who loves the world and the Father is not in such a person. It’s black and white for John. Either you are in or you are out. Either you are holy or you are not. There is no to and fro between the two states. In 2:18 he refers to the antichrist and says that there are many antichrists then and even the antichrist himself, and because of that they knew it was the “last hour.” This is why John wants them to remain sinless because the time of Christ’s return is so close and they will see Him and not be ashamed when he comes.
John warns them of seducers who try to lead them astray to fall back into sin and into disbelief. They are to pay no attention but to continue in their walk. John has great confidence that the holy ones will make it and that the deceivers will not get through to them - Why? Because they have “the anointing of the Spirit” and cannot sin. This is the holy Body of Christ, his precious righteous Church.