As we approach verses 8-10 of 1 John, it is important to stay within the context of the Gnostic controversy so we avoid concluding that John is making a point other than the one he is making. The verses read, “If we say that we have no sin, we are deceiving ourselves and the truth is not in us. If we confess our sins, He is faithful and righteous to forgive us our sins and to cleanse us from all unrighteousness. If we say that we have not sinned, we make Him a liar and His word is not in us” (1 Jn.1:8-10).
John previously established that “walking” in darkness, later to be known as “practicing sin” or “practicing lawlessness” (1 Jn.3:4), eliminates fellowship with God and with those “walking” in the light. The goal for the Christian is to walk in the light as “God is light.” This was emphasized because a certain branch of Gnostic teaching stated that we could be spiritually healthy (have fellowship with God) while doing anything we wanted in the physical realm. This would amount to the idea that there is no such thing as sin; nothing morally right or wrong.
As John states, “If we say we have no sin…,” he is refuting the Gnostic idea that no form of human behavior is wrong (sin). Some have referenced this verse in support of the idea that it is inappropriate for a Christian to assume he / she can overcome sin, but John is not attempting to establish the idea that Christians will or must continue to sin. We can be confident of this in light of the idea that he is refuting Gnostic influence and that he states, “…I am writing these things to you so that you may not sin” (1 Jn.2:1). If the Gnostic idea was true, all behavior would be acceptable, there would be no such thing as sin and if there is no such thing as sin, there is no need for an atonement.
He further emphasizes that if we take such a position, “we are deceiving ourselves and the truth is not in us,” indicating that the Gnostics do not represent truth but, rather, deception.
Contrary to denying the existence of sin, we are to “…confess our sins…” To confess means to agree with God. We are agreeing that that which He reveals to be morally wrong is, in fact, morally wrong. As well, the confession is not simply a general confession, but we are to confess our sin. This would involve agreeing with God about the sin of which we are personally guilty. As we do this in sincerity, “…He is faithful and righteous to forgive us our sins and to cleanse us from all unrighteousness.” Notice that God’s goal is not simply to forgive us (though this is wonderful and important) but to cleanse us from moral impurity; to lead us to have victory over sin. It is often the case that we emphasize forgiveness and overlook cleansing for which the blood of Christ was shed (1 Jn.1:7).
In our contemporary setting, we have many who claim to have fellowship with God but disagree with God about certain things He calls sin. This is a grave error as forgiveness and cleansing cannot take place in such cases. This happens as a result of outright rebellion or because of sentimental feelings toward the people who are in bondage to certain types of sin (“he / she is such a nice person”).
John then reiterates the idea adding a slightly different result than “deceiving ourselves” as he states, “If we say that we have not sinned, we make Him a liar and His word is not in us.” The denial of sin amounts to calling God, who reveals certain things to be sin, a liar. It should be clear that this is not a good idea.
In conclusion, we can say that God has communicated a moral law (Light), He has lived by the moral law (God is Light), He calls us to live according to the moral law (walk in the Light), violating the moral law is sin which eliminates fellowship with God and with those who walk in the light and that deliverance from sin involves the atonement in Christ (the blood of Jesus) and confession (agreeing with God about moral issues).