But if we walk in the light as He Himself is in the light, we have fellowship with one another, and the blood of Jesus His Son cleanses us from all sin.
1 John 1:7 HCSB
A sin is a wound on our soul.
When we are unborn in Christ, that wound is a festering sore that keeps us unclean and keeps us from the Kingdom of God; it is a sore the devil delights in festering since he knows it keeps us from God.
When we are reborn in Christ and confess our sins, the blood of Jesus cleanses and heals those wounds; but like all wounds, a scar is formed. A scar is a remembrance of the wound; it carries no real pain, just memories to learn from. Our sins are cleansed before God, but our scars are for us to remember them so that we do not forget the pain and commit the sin again.
When we believe in Jesus Christ and are truly reborn, the blood of Jesus cleanses us from all of our sins and heals our wounds.
We need to confess our sins, ask for forgiveness, accept Jesus Christ as our Lord and Saviour, and follow His instructions as presented in the Bible, not by the customs of man.