Should we confess past sin we did in the past to people we have wronged or should we just confess it to God and not do it again if it doesn’t affect that person today ?
My short answer is no. Let's look at the Scripture most used to support this doubtful practice:
"This is the message we have heard from him and proclaim to you, that God is light, and in him is no darkness at all. 6 If we say we have fellowship with him while we walk in darkness, we lie and do not practice the truth. 7 But if we walk in the light, as he is in the light, we have fellowship with one another, and the blood of Jesus his Son cleanses us from all sin. 8 If we say we have no sin, we deceive ourselves, and the truth is not in us. 9 If we confess our sins, he is faithful and just to forgive us our sins and to cleanse us from all unrighteousness. 10 If we say we have not sinned, we make him a liar, and his word is not in us" (1 John 1:5-10).
If we extract verse 9 from the passage, it might seem that we need to confess every sin, to God, a priest, or some other person. But we need to see the verse in context. The context deals with our fellowship with God, and that we are to walk in the light as He is in the light, and we have true fellowship with each other and the blood of Jesus cleanses us from all sin.
Now, look at verse 8. It says that if we say we have no sin we deceive ourselves and the truth is not in us. What this says to us is that if we don't acknowledge that we are sinners needing a Saviour, we are deceiving ourselves and the truth is not in us. If that is the case, we are not walking in the light, our sins are not cleansed by the blood of Jesus. In other words, we are not saved.
But here is verse 9: What this says is if we declare that we are sinners needing a Saviour, He forgives our sins and cleanses us from all unrighteousness. What this means is that if we declare to God that we are sinners, we have true fellowship with God and the blood of Jesus really does cleanse us from all sin. Then verse 10 follows this up by telling us that if we say we have not sinned, then we make God our to be a liar and His Word is not in us.
The context does not support the notion that we have to confess every sin to God or to anyone else. It is to acknowledge that we are sinners, and that the crucial step to salvation in Christ is to declare this before God. Then we are totally forgiven and cleansed from all unrighteousness, negating the need for any further confession of specific sins.
What this shows us is that we need to carefully consider the context of a verse before we try to apply it, otherwise we end up getting the wrong end of the stick and start believing and teaching false doctrine.
Also, the quest for some to achieve sinless perfection is a road to nowhere. We won't stop being sinners until the day we die. If a person thinks they have achieved sinless perfection and say that they are no longer sinning, they are effectively saying they have no sin, thereby deceiving themselves and the truth is no longer in them. They are making God out to be a liar.
We are not afraid to declare our sinfulness to God, because we have total trust in what Jesus did for us on the Cross, taking the full penalty for all our sin, and that His blood cleansed us from all unrighteousness, and He gave us His own pure righteousness as a free gift. But, as Paul says, "There is nothing good in me, that is, in my flesh". We always have struggles with the flesh, but our faults and failings in the flesh do not go right down to our hearts. This is explained by Paul where he says that in his heart he strongly desires to follow God's moral law, but in his flesh he ends up doing what he doesn't want to do, and fails to do what he should be doing. He resolves the issue by saying that the law of the Spirit of life in Christ has set him free from the law of sin and death.
