Confess, but repent
I remember undertaking the task of repainting a dock on an empty pond at a Girl Scout camp in Southern California. You have to scrape the old paint before you put on the new, but you also have to use a very thick, oil-based paint to redo the dock. Why? It helps preserve it from rotting. As my friend and I undertook the task, the weather got warmer as the day progressed, the task was less than interesting at some point, and we got a little mischievous at some point. We were at the point of applying the paint when all of a sudden, an all-out 'let's paint each other' rebellious attitude overtook us. There we were, swiping oil-based blue marine paint across each other's faces, arms, legs, and even our painting clothes. We were a mess by the end, but we had a few good laughs along the way. But then...we realized that the paint would not wash off! It required turpentine to remove it! As you can imagine, it took us way longer to remove that stuff than it did to have that momentary insanity we called 'fun'. That is how sin is - it is momentary, but with a very lasting effect that is almost impossible for us to remove ourselves.
Wash yourselves and be clean was almost impossible - we each needed the assistance of the other to remove all the signs of the paint. Even then, we weren't without telltale signs of having undergone the folly of the day, for our skin was reddened, dry, and very irritated from all the scrubbing with turpentine! Sin isn't easy to remove from our lives - there will be telltale signs of it if all we do is endeavor to wash ourselves clean from its nastiness. We need God's help to be truly clean - “Come now, let’s settle this,” says the Lord. Though your sins are like scarlet, I will make them as white as snow. Though they are red like crimson, I will make them as white as wool." (vs 18) There is only so much we can do for ourselves - such as confession of our sin and repentance (turning away from it). We require a good deal 'scrubbing up' that isn't possible alone. We need God to remove the very evident sign of sin in our lives - completely, without harm, and as only his blood can do. We needed the aid of turpentine to be 'clean' from the marine paint. God needed only one thing to leave us perfectly clean - the blood of his Son, the perfect sacrifice for the sins of all mankind.
Confession is one part of 'being cleansed'. We also need repentance in order to really 'walk clean'. Repentance is more than just asking God for forgiveness - it means those sins are no longer our pursuit. We 'put them out of sight', not by masking over them, but by having God's help to remove ourselves from their influence any longer. Eventually, the paint on the brushes dried and we could no longer pursue the folly of flinging paint at each other. Sin doesn't quite behave the same way, though. It lingers and wants to get us all dirty again. If we are to be free of its 'attachment' to us any longer, we need to walk away from it. We do this by first having a change of thinking about the pursuit of that sin. Since all action begins with thought, whether we believe it or not, our thinking requires change if we are to walk away from the pursuit of that sin. When we change our mind, we change our behavior. If you put down the paint brush, no more paint will be hurled your way! Confession allows us to get out the words that show we no longer want to pursue that sin, while repentance incorporates new actions, so we won't go that direction any longer. Just saying!