Question: "Why do we need to confess our sins if they have already been forgiven (1 John 1:9)?"
Answer: The Apostle Paul wrote, "We praise God for the wonderful kindness he has poured out on us because we belong to his dearly loved Son. He is so rich in kindness that he purchased our freedom through the blood of his Son, and our sins are forgiven. He has showered his kindness on us, along with all wisdom and understanding (Ephesians 1:6-8, NLT). This is referring to salvation, where God has taken our sins and removed them from us “as far as the East is from the West” (Psalm 103:12). This is the judicial forgiveness that God gives us upon receiving His Son Jesus Christ. All the past, present, and future sins are forgiven on a judicial basis, meaning that we will not suffer eternal punishment for our sins. We still often suffer consequences of sin while we are here on earth, however, which brings us to the question.
The difference between this passage and the verse in 1 John is that John is dealing with what we call "familial" forgiveness—like that of a father and a son. For example, if you do something wrong to your father—fall short of his expectations or rules—you have a hindered fellowship, but you are still a son. That fellowship is hindered until you admit to your father that you have done wrong. It works the same way with God; your fellowship with Him is hindered until you confess that sin. Then the fellowship is restored. This is “relational” forgiveness.
“Positional” forgiveness is that which is obtained by every believer in Christ. In our position as members of the Body of Christ, we have been forgiven of every sin we have ever committed or ever will commit. The price paid by Christ on the cross has satisfied God’s wrath against sin, and no further sacrifice or payment is necessary. When Jesus said, “It is finished,” He meant it. Our positional forgiveness was obtained then and there.
Confession of sin, according to 1 John 1:9, will help to keep us from the discipline of the Lord. If we fail to confess that sin, the discipline of the Lord is sure to come until we do confess it. As stated previously, our sins are forgiven at salvation (positional forgiveness), but our fellowship with God on a daily basis needs to stay in good standing, which cannot happen with unconfessed sin in our lives (relational forgiveness). Therefore, we need to confess our sins as they occur in order to keep that right fellowship with God.