1Jn 1:5-10
5 This 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.
6 If we say that we have fellowship with him, and walk in darkness, we lie, and do not the truth:
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 cleanseth us from all sin.
8 If we say that we have no sin, we deceive ourselves, and the truth is not in us.
9 If we confess our sins, he is faithful and just to forgive us our sins, and to cleanse us from all unrighteousness.
10 If we say that we have not sinned, we make him a liar, and his word is not in us.
I think we need to get some definitions according to the context of the verses right before we can put them together to give a contextual interpretation of the texts above.
DARKNESS: It seems to me that the word 'darkness' as used in these texts does not have the same meaning even though they are linked.
"...God is light, and in him is no darkness at all." What does darkness mean in this text in contrast to light? I think John is describing God's nature. The nature of God is light (pure) and he does not have anything that contradicts his pureness (darkness). Hence, 'light' and 'darkness' is a reference to God's person.
"..If we say that we have fellowship with him, and walk in darkness..." What does 'darkness' mean in this text? It is not referring to 'nature ' as it is clear in comparison with the usage in verse 5. It is a comparison to a relationship. Two people in fellowship are in the same boat or world; they agree to the same thing. Hence, he who is in darkness, in this verse is in another boat but deceives himself that he is in the same world as the one he thinks he has fellowship with. They do not agree that God is only light (pure). The 'extra' belief that God is both light and darkness portends that this person is not saved, that is, not in the kingdom.
Having seen the different definitions or applications of the word 'darkness', we look at the text.
It is my opinion that verse 8 is dealing with doctrine. "If we say that we have no sin..." "If we" is John's way of taking a temporary position or assumption on a matter by 'including' himself. "if we say...we HAVE NO SIN..." to me, seems to be a reference to the doctrine of the original sin of Adam and Eve. If we say there was no fall in the Graden and that the human race is not in sin, it will be obvious that the blood of Jesus is futile. Hence, the shedding of the blood contradicts the belief that man has no sin and does not need atonement. If the original sin of Adam is denied, atonement is denied! Therefore, such a person who believes such is not saved and not in the same boat as Jesus. The atoning blood of Jesus will not be effective on such a person. He is not saved; he is in darkness. Hence, verse 8 is doctrinal.
Verse 9 addresses the contrast, that is, he who understands and agrees to be a sinner. Such a one will receive the atonement. Jesus will be of use to such a person and he will be forgiven and be in fellowship with Jesus.
Verse 10 deals with the result of the doctrine addressed in verse 8. Wrong beliefs will bring the wrong lifestyle. Denial of the Adamic sin will bring about a sinful life. Orthodoxy produces orthopraxy. Verse 10 portends the position of a person who denies Adam's sin on Jesus. How can you deny the doctrine of original sin and still be in fellowship with Jesus? It does not make sense. Hence, John arrives at the fatal result of the earlier assumption that 'if we say we have no sin'.
An example that seem to be in support of my analysis is 1Jn.2:9,11.
“He that saith he is in the light, and hateth his brother, is in darkness even until now.” (1Jn 2:9)
The hatred of a brother in the text is predicated on the doctrine of 1Jn.1:8. The text of 1Jn.2:9 is the result of the doctrine. This is further reiterated and its result is further expounded in verse 11.
“But he that hateth his brother is in darkness, and walketh in darkness, and knoweth not whither he goeth, because that darkness hath blinded his eyes.” (1Jn 2:11)
Another example given by John is the case of Cain and Abel.
1Jn 3:11-12
11 For this is the message that ye heard from the beginning, that we should love one another.
12 Not as Cain, who was of that wicked one, and slew his brother. And wherefore slew he him? Because his own works were evil, and his brother's righteous.
Cain was in darkness while Abel was in the light. Cain hated Abel till he killed him because his works were evil. Cain's works were 'EVIL'. It is clear that Cain was in darkness and had no fellowship with the father!
Abel's faith determined what to sacrifice. Heb. 11:4. Likewise, Cain's doctrine determined his sacrifice because his sacrifice was not of faith. Heb.11:4.
Outside the book of First John, there is a notable scripture concerning Cain. It is called 'The way of Cain'.
“Woe unto them! for they have gone in the way of Cain, and ran greedily after the error of Balaam for reward, and perished in the gainsaying of Core.” (Jud 1:11)
'The way of Cain' is his doctrine. Certain who crept into the church are described in semblance to the 'way of Cain'. They turned (exchanged) the grace of God into (for) Lasciviousness. The Greek word translated 'turned' is 'metathitemi' meaning 'to exchange' or 'to transpose'.
The term 'Grace of God' is a reference to the core doctrines of Christianity. Atonement is a core doctrine and it is predicated on the fact of the Original Sin. Rom. 5:12. 'Lasciviousness' is the term Jude gave to their doctrine because it leads to a life of lasciviousness. Here, we see orthodoxy turning into orthopraxy.
Hence, Cain and Abel is a worthy example given by John.
These are the words of Adam Clarke concerning 1Jn.1:8:
"It is very likely that the heretics, against whose evil doctrines the apostle writes, denied that they had any sin, or needed any Savior. In deed, the Gnostics even denied that Christ suffered: the Aeon, or Divine Being that dwelt in the man Christ Jesus, according to them, left him when he was taken by the Jews; and he, being but a common man, his sufferings and death had neither merit nor efficacy."
"We deceive ourselves - By supposing that we have no guilt, no sinfulness, and consequently have no need of the blood of Christ as an atoning sacrifice: this is the most dreadful of all deceptions, as it leaves the soul under all the guilt and pollution of sin, exposed to hell, and utterly unfit for heaven."
"The truth is not in us - We have no knowledge of the Gospel of Jesus, the whole of which is founded on this most awful truth - all have sinned, all are guilty, all are unholy, and none can redeem himself. Hence it is as necessary that Jesus Christ should become incarnated, and suffer and die to bring men to God."
Adam Clarke’s commentary on 1Jn.1:8. Electronic version.
This agrees with my opinion that 1Jn.1:8 is a doctrinal issue. The experimental was given in verse 10.
My two pence.