1 John 1:8-10

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 has no place in our lives.

(v8-10, NIV)

What's the difference between verse 8 and verse 10? Verse 8 begins with claiming to be without sin. Verse 10 begins with claiming to have not sinned. At first glance, they seem pretty much the same. In both instances, the person is claiming some sort of separation from sin. However, in both cases, this causes us to be without the truth, or a liar. The first, to be without sin, is a claim to be without sin in our nature. This is similar to those who say that humans are generally "good" people. They believe that it's in our nature to do "good". I have a feeling that this is simply a down-play of sin, since we know that everyone sins. The sins they do see "good" people doing (including themselves I'm assuming), they down-play it by comparing it to other people's sins. Thus, they think they are still good while they still sin. They may say things like "sure, I punched a pregnant lady in the stomach, but at least I didn't murder someone like that convict I read about in the newspaper". Okay, that was terrible and I hope none of you is doing that. But even if it was a "white lie", that's still terrible because it's still calling sin something that it is not. It is in our nature to sin. Without God, we'd simply keep on sinning and doing what is evil. Sure, some people try to be "good", but their nature is still a sinner. Don't try to say otherwise, you're simply deceiving yourself; the truth is not in you.

Now, I must be careful because as mentioned before, John continues to use the word "we". I am included in this as is John and his readers. Don't think that just because you go to church or just because you prayed some prayer on time that you're immune from this happening to you. I may very well be saying in my heart that I am not a sinner by nature. That's a lie and I am deceiving myself. My nature is to sin. Do not deceive yourselves.

Added: It is true that when you make these claims, we are lying because what you are saying is untrue. However, these people who are saying it believe what they are saying to be true. They believe that they have never actually sinned in their life. Or, they may actually believe that they are good by nature. Regardless of whether they think it's true or not, the point is that they know what God thinks. And regardless of what God says, they will think their own way. They know God says that we are sinners by nature and by conduct. In light of this, they still stand to their claim that they are without sin in conduct or nature. Since they know what God says and claim the opposite, they are calling God a liar. In addition, since God is light and God is truth, the truth is not in them.