What then is confession? The apostle did not say that confession is praying that God would forgive our sins. Many prayers and pleadings before God for forgiveness are not confessions. Nor did the apostle say that confession is just to utter something with our mouth. What the apostle said was that we have to acknowledge the sin, to treat the sin as sin. Confession means that we stand on the same ground as God does, admitting before God that our deed is indeed a sin. The moment you confess your sin, you will be forgiven. To confess is not to plead for forgiveness. Forgiveness is the Lord Jesus’ business. What you have to do is judge the sin as sin. You have to judge it, acknowledge it, and confess that it is wrong. You have to take sin as sin and treat sin as sin. What you must confess before God is that a sin is indeed a sin. If you confess your sins, God is faithful and righteous to forgive all your sins and unrighteousness. Just as a sinner receives the forgiveness of sins through the work of the Lord Jesus, a Christian receives the forgiveness of sins from God by judging his sin as sin and through the work of Christ upon him. Simply put, confession is our saying that something is sin because God says that it is sin. For example, suppose a brother’s child goes out into the street and plays with some bad children. Because he picks up foul language and gets into mischief, the brother brings in the children who have been leading his son to do these things and tells them that they are wrong and that they should no longer play with his child. He also tells his son not to play with them anymore. The child says that he wishes to confess that he is wrong and asks for forgiveness. But although he says this with his mouth, in his heart he is thinking of a way to sneak out the back door to go out and play again. He does not stand one with his father. At issue here is not forgiveness, but whether or not we acknowledge something as sin.
Confession means that whatever God considers as sin I also consider as sin. It means that I say the same as what God has said. If God says that it is wrong, I say that it is wrong also. Confession is your recognition and declaration of sin. When you do it, God forgives your sins and cleanses you from all unrighteousness. He is not forgiving you because of your confession; He is forgiving you because of the work of the Lord Jesus. His blood is the basis of everything in this matter. But through confession, the blood produces forgiveness. Salvation is by the blood through faith. But forgiveness is by the blood through confession. This is like saying that tap water comes by the source of the water department through the pipes. In the same way, forgiveness comes by the blood through confession.
(Gospel of God, The (2 volume set), Chapter 25, by Watchman Nee)