This verse is often used as an attempt to support that man can never stop sinning, but it must be viewed in its proper context.
1 John 1:5This then is the message which we have heard of him, and declare unto you, that God is light, and in him is no darkness at all. 6If we say that we have fellowship with him, and walk in darkness, we lie, and do not the truth: 7But 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 cleanseth us from all sin. 8If we say that we have no sin, we deceive ourselves, and the truth is not in us. 9If we confess our sins, he is faithful and just to forgive us our sins, and to cleanse us from all unrighteousness. 10If we say that we have not sinned, we make him a liar, and his word is not in us.
If 1 John 1:8 means that we can never say ”I have no sin” at ANY TIME in our lives, not even for one second, then the only outcome is that we sin around the clock. It would even mean that we still have sins one second after that we have repented! What is the big idea with repenting if we always sin and can never stop? We can read in the same passage that we can be CLEANSED if we confess our sins. Surely we are free of sins when we are cleansed from sins, or can we be cleansed from our sins at the same time as we still have sins? That doesn’t make much sense.
We can also read in the passage that if we are walking in darkness, we do not have fellowship with God and we therefore LIE if we would still say that we do, and the truth is not in us! BUT IF we walk in the light as he is in the light, the blood of Jesus Christ cleanseth us from all sin. It is those who walk in darkness who are liars if they claim to know God, and not those who walk in the light.
The significance of 1 John 1:8 is that none of us can say ”I don’t have any sin on my record so I don’t need a Savior” because we have all sinned. ”If we say that we have not SINNED, we make him a liar, and his word is not in us.”
Apart from the above passage, John also tells us elsewhere in his writings that we can obey the commandments and live holy. John doesn’t contradict himself by saying in one verse that we constantly sin and can’t stop, only to give the exactly opposite message in other verses. John tells us that that it’s totally unnatural for a christian to sin!
1 John 2:1 My little children, these things write I unto you, that ye sin not. And IF any man sin, we have an advocate with the Father, Jesus Christ the righteous:—3 And hereby we do know that we know him, if we keep his commandments.4 He that saith, I know him, and keepeth not his commandments, is a liar, and the truth is not in him.5 But whoso keepeth his word, in him verily is the love of God perfected: hereby know we that we are in him.6 He that saith he abideth in him ought himself also so to walk, even as he walked.
1 John. 5:2 By this we know that we love the children of God, when we love God, and keep his commandments.3 For this is the love of God, that we keep his commandments: and his commandments are not grievous.4 For whatsoever is born of God overcometh the world: and this is the victory that overcometh the world, even our faith.
2 John. 1:6 And this is love, that we walk after his commandments. This is the commandment, That, as ye have heard from the beginning, ye should walk in it.
3 John 1:11Beloved, follow not that which is evil, but that which is good. He that doeth good is of God: but he that doeth evil hath not seen God.
If we would embrace the faulty understanding of 1 John 1:8, are we also willing to be consistent and say the apostle John had no truth in him?