One of my favorite passages from scripture is 1 John 1.5-10, one with which we are all familiar:
5 This is the message we have heard from him and proclaim to you, that God is light and in him there is no darkness at all. 6 If we say that we have fellowship with him while we are walking in darkness, we lie and do not do what is true; 7 but if we walk in the light as he himself is in the light, we have fellowship with one another, and the blood of Jesus his Son cleanses 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 who is faithful and just will forgive us our sins and 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.
If you have a sensitive conscience and an awareness of your own sinfulness, if you know yourself to some extent and therefore know that more often than not you fall well short of where you should be, it may be easy to be intimated by John's message here. He says, after all, that if we do not walk in the light, we are not in fellowship with God. Who among us can claim for himself that in him there is no darkness at all? But as a matter of fact, I think such a person, for the very reason that he is aware of his unworthiness, is assured by John's words that he does have fellowship with God.
John affirms that those who are in the darkness and who ascribe darkness to God by making him a liar are those who say that we have no sin (v. 10). Likewise those persons are self-deceived and lack the truth. Those persons, if anyone, are in the darkness. The darkness represents ignorance and deception, whereas light is associated with the truth and with reality. Therefore John introduces God by an association to light, but says that our fellowship with him means a life lived in the truth; and per v. 8, having the truth within ourselves means a recognition of our sin.
Notice then what this means: precisely those persons who feel their own sinfulness and distance from God's desired goal are already in fellowship with God; they demonstrate that they are in the light and they've had fellowship with God, by the very fact that they realize their own sinfulness before God. On the other hand, those persons who simply cannot be convinced that they do anything wrong, who have no sense that their life is not well-lived -- those persons are lacking in fellowship with God and are in the darkness.
This text, then, ought to be a comfort to those persons who might be intimidated by it. Through the fact that you see darkness in yourself and recognize it as such, you demonstrate that you have been in fellowship with God all this time. It is God himself within your heart that reveals this to you. He doesn't want to cut you off; he doesn't want to cast you away. On the contrary, he gently turns your eye to the things you do and their true nature so that you may turn away from them, no longer to harm yourself or be cut off by pangs of conscience from his fellowship.