I've had a long and tempestuous relationship with 1 John 1:9. It's a verse we teach to the children quite early:
If we confess our sins, He is faithful and righteous to forgive us our sins and to cleanse us from all unrighteousness. (NASB)We're right to do so! It has been an anchor for generations of Christians who have found they just don't measure up.
But there's another side to it. Let me illustrate with a story:
When I was a teen, I was in a Bible class. The teacher asked, "Which sins did Christ die for?"
Someone replied, "The sins we confess".
The teacher asked, "So if you die while sinning, do you then go to hell? After all, that would be a sin Christ didn't die for."
That was a watershed moment in my life.
It didn't occur to me immediately, but I eventually realized that I (along with many others, apparently) had come to believe that confession of sins was somehow meritorious. I'd never have said I earned forgiveness by confession, but I effectively believed it. Perhaps I'd have said that confession makes me forgiveable or something... but I did definitely believe that confession was a sort of a work I did to gain forgiveness.
Eventually I came to see that God forgives because of the blood of Christ, not because I have confessed. I came to understand that God forgives my sins whether I confess them or not. I don't see any other way to understand Romans 4:5–8.
So what's the point of 1 John 1:9? I am convinced the point of 1 John 1:9 is really assurance of forgiveness. It's not telling us how to gain God's forgiveness, but it's telling us how to be assured of it. When we have sinned, and that sin seems too big, and it seems to obscure God's face, and it seems to cut us off from God, we can look at 1 John 1:9 and be sure that God has forgiven it.