God is light. In him there is no darkness at all. If we claim to have fellowship with him yet walk in the darkness, we lie and do not live by the truth. But if we walk in the light, as he is in the light, we have fellowship with one another, and the blood of Jesus, his Son, purifies us from all sin.In the first set of verses, John instructs us how to live in fellowship with God. In contrast to the mindset of many Jews of the day, in which fellowship (or favor) with God was equated with having a Jewish heritage, John stresses that a relationship with God comes by walking in obedience to his commands (see supporting verses in 2:3-6). God is light, so if we walk in darkness, how can we have fellowship with God?
(1 John 1:5b-7, NIV)
If we claim to be without sin, we deceive ourselves and the truth is not in us. If we confess our sins, he is faithful and just and will forgive us our sins and purify us from all unrighteousness. If we claim we have not sinned, we make him out to be a liar and his word is not in us. My dear children, I write this to you so that you will not sin.
(1 John 1:8-2:1a, NIV)
If we are to have fellowship with God, then we should walk in the light. Walking in the light results in obedience to God and abstinence from sin. Doesn't this seem to be John's point? But notice the first verse of the next set: "If we claim to be without sin, we deceive ourselves and the truth is not in us." On first pass, it may seem as though John is saying that no one can ever be without sin. Besides, he says, "if we claim...", and "we" includes all of his audience, right? But given that John just said that we need to walk in the light (i.e., abstain from sin) in order to have fellowship with God, I think we need to look a little closer at what John is trying to say before drawing theological conclusions from this passage.
When I was reading this passage, I had a new insight into what John could be trying to communicate. After introducing the topic (which is how to walk in fellowship with God) in the first set of verses, John goes on to give a chronological order of events that apply to those seeking a relationship with God. Then, he gives us the take-home lesson. Let me give you the digest version of John's message:
- [Topic] - We can't walk in sin and be in fellowship with God at the same time.
-  - If we say we don't have sin, then we're liars.
-  - After we realize that we have sinned, we need to confess them and repent. Then we'll be forgiven.
-  - But, if we then say that we've never sinned in the first place, then we make God out to be a liar.
- [Lesson] - I (John) write this so that you won't sin (so that you can be in fellowship with God).
From the above outline, we can see a progression of thought. The goal is to walk in fellowship with God. If we want to accomplish that goal, then we need to stop walking in sin. But when we first hear the message that we need to stop walking in sin (before coming into a relationship with God), many of us deny that we are doing so. "I'm a pretty good person," we may think. John says that if we claim to be without sin--without need of a Savior--then we are deceiving ourselves. When we finally come to realize that we are sinful (which John's audience supposedly already has), then we come to repentance and receive God's forgiveness, being counted as righteous through Christ. But after our debt of sin is removed from us, John is warning us against the temptation to say that we never sinned in the first place. If we say we have never sinned, we essentially say that we have earned our standing before God apart from Jesus. Thus, we make God out as a liar because He declared that mankind has fallen short of God's glory and needs to be reconciled to Him through His Son Jesus. John concludes by telling us his motivation for writing this passage to us: "I write this to you so that you will not sin."
In conclusion, I believe that John is encouraging his brothers and sisters in Christ to avoid sin so that they will draw closer to God through fellowship with Him. He points out a couple ways that people can deceive themselves into thinking they don't need to deal with sin in their life (either because they don't have sin or they don't need God). If we fall into either trap of self-deception, we fall into sin, and we fall out of fellowship with God. Thus, with earnest zeal, John illuminates these common pitfalls so that we will not fall into them. His motivation in writing these words is to keep us from sin so that we will walk in fellowship with God. I do not think he is trying to tell us that our lives are hopelessly stained with sin on a daily basis and that we can never strive for righteousness. In fact, I think he is saying the opposite. We are cleansed from the stains of sin when we repent before God, and from that point on, we are free to live righteously for Him. Does that mean we ever grow beyond the need for a Savior? No. But we can--contrary to the thinking of some Christians--get better and better at serving Christ each day. The more we "die to self" and "live for Christ" each day, the more righteous we can become. Is there a limit to how righteous we can become in word and deed as followers of Christ on this earth? ... That, my friends, is a topic for another day.