Question: "Why do we need to confess our sins if they have already been forgiven (1 John 1:9)?"
Answer: The apostle Paul wrote, “To the praise of his glorious grace, which he has freely given us in the One he loves. In him we have redemption through his blood, the forgiveness of sins, in accordance with the riches of God's grace that he lavished on us with all wisdom and understanding” (Ephesians 1:6-8). This forgiveness is referring to salvation, in which 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 Jesus Christ as Savior. All our past, present, and future sins are forgiven on a judicial basis, meaning that we will not suffer eternal judgment for our sins. We still often suffer consequences of sin while we are here on earth, however, which brings us to the question at hand.
The difference between Ephesians 1:6-8 and 1 John 1:9 is that John is dealing with what we call “relational,” or “familial,” forgiveness—like that of a father and a son. For example, if a son does something wrong to his father—falling short of his expectations or rules—the son has hindered his fellowship with his father. He remains the son of his father, but the relationship suffers. Their fellowship will be hindered until the son admits to his father that he has done wrong. It works the same way with God; our fellowship with Him is hindered until we confess our sin. When we confess our sin to God, the fellowship is restored. This is relational forgiveness.
“Positional” forgiveness, or judicial 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 will help to keep us from the discipline of the Lord. If we fail to confess 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 daily fellowship with God needs to stay in good standing (relational forgiveness). Proper fellowship with God cannot happen with unconfessed sin in our lives. Therefore, we need to confess our sins to God as soon as we are aware that we have sinned, in order to maintain close fellowship with God.