Regretfulness about our sinful past after Christ has cleansed us is not a very useful tool in our Christian walk for the born-again believer.
When we have been forgiven of our sins and God remembers them no more against us, continually calling them to mind does nothing useful for us.
Our focus as Christians ought not to be the past regrets but we ought to be focused on the fullness and newness of life Christ gave us when He changed us into a new creation. Romans 6
Moving forward in holiness and service to God will only be hindered by sadness and regret over something that is in the past and will not be changed.
Only the devil resurfaces memories of past sins to debilitate us, keeping us from speaking boldly about sin. There are those who act as though we have no authority to speak against sin because we were once sinners. If this were true then no one would ever have the authority to speak against sin, because all have sinned.
Speaking openly of our past to show others what a wonderful thing Christ did in saving and changing us is a good thing, but if it brings debilitating sadness and regrets it offers no hope for the ones who remain in their sins. Why bother to confess and repent if the agony of the sin torments them for the rest of their lives.
God's forgiveness when we confess is the complete extinguishing of any guilt, there should not be a residue that lingers as we grow in Christ.
Regretting past forgiven sins does not bring any more forgiveness than we had the first time, in fact the regret and sadness over past forgiven sins could very well be a lack of faith that God has forgiven and forgotten. It might also be a fear of man, that others will hold our past forgiven sins against us.
We need not fear what man thinks. No child of God who loves you will hold against you past forgiven sins. If we encounter someone who says they are Christian and want to treat us disrespectfully over our past, then they do not love us, do not understand the forgiveness of God and will not be interested in being a growing thriving companion for us on our journey.
Philippians 3:13-14 - " Brothers, I do not count myself to have attained, but this one thing I do, forgetting those things which are behind and reaching forward to those things which are ahead, 14 I press towards the goal to the prize of the high calling of God in Christ Jesus."
I am thankful for the loving Savior Who encourages me with His Word every day. I have encountered "Christians" who love to think evil things about me as though I am still in the past, never having moved beyond that past. I pay no attention to them, I have moved on from them. If they ever repent of their self-righteousness and want to reconcile I would be ready, but until that happens I am going down that path with Christ without them.