Question: "What is the danger/consequence of unconfessed sin?"
Answer: First John 1:9 says, “If we confess our sin, he is faithful and just to forgive our sin and to cleanse us from all unrighteousness.” This verse is written to Christians and hinges on the word if. God offers total pardon for every sin His children commit IF we confess it to Him. The word confess implies agreeing with God about how bad our sin is. Repentance, or turning away from it, is part of this confession. For those who have not been pardoned by the blood of Jesus, every sin is unconfessed and unforgiven. Eternal punishment awaits those who refuse to repent of their sin and accept Jesus’ sacrifice for it (2 Thessalonians 1:8–9; John 3:15–18). But what about a Christian with unconfessed sin?
According to Scripture, all our sin was paid for when we accepted Jesus’ sacrifice on our behalf. Second Corinthians 5:21 says, “He made Him who knew no sin to be sin on our behalf, so that we might become the righteousness of God in Him.” When we make that divine exchange at the cross, God chooses to see us as righteous. It is not our righteousness but the righteousness of Christ that God sees (Titus 3:5). He switches accounts with us: our tarnished rap sheet for His perfect record. We have the full approval and acceptance of God from then on.
But what happens when we sin after receiving that perfect record? Imagine standing by a south window on a cold winter day. The air is frigid, but the sun is shining through the window. It begins to warm you, and you bask in its glow. Then you pull the drape closed. Instantly, the warmth stops. Is it because the sun has stopped shining? No, it is because something has come between you and the sun. The moment you open the drape, the sun can warm you again. But it is up to you. The barrier is inside the house, not outside.
Unconfessed sin works like that drape. God delights in His children (Psalm 37:23; Romans 8:38–39). He desires to bless us, fellowship with us, and shower His approval upon us (Psalm 84:11; 115:13; 1 Samuel 2:30). He wants us to bask in the warmth of His smile. But when we choose sin, we build a barrier between ourselves and our holy Father. We pull the drape on fellowship with Him and begin to feel the chill of spiritual loneliness. Many times, we angrily accuse God of leaving us when, in truth, we have left Him. When we stubbornly refuse to repent, we will be disciplined by our loving Father (Hebrews 12:7–11). The Lord’s discipline can be severe, even leading to death when a heart has hardened to the point of no return (1 Corinthians 11:30; 1 John 5:16). God longs for restored fellowship even more than we do (Isaiah 65:2; 66:13; Matthew 23:37; Joel 2:12–13). He pursues us, disciplines us, and loves us even in our sin (Romans 5:8). But He leaves our free will intact. We must pull back the drape by confessing and repenting.
If, as children of God, we choose to remain in our sin, then we choose the consequences that go with that choice. Broken fellowship and lack of growth result. However, those who persist in sin need to reexamine their true relationship with God (2 Corinthians 13:5). Scripture is clear that those who know God do not continue a lifestyle of unrepentant sin (1 John 2:3–6; 3:7–10). A desire for holiness is a hallmark of those who know God. To know God is to love Him (Matthew 22:37–38). To love Him is to desire to please Him (John 14:15). Unconfessed sin gets in the way of pleasing Him, so a true child of God wants to confess it, change it, and restore fellowship with God.