We can do nothing about the past except make necessary confession. And when confession is made, the Bible promises: "If we confess our sins, he is faithful and just to forgive us our sins, and to cleanse us from all unrighteousness" (1 John 1:9).
By confession, sin is placed under the cleansing blood of the Lord Jesus Christ, and when it is under the blood, it does not condemn any longer.
Unless the past is dealt with, one is not prepared to live in the present nor to go on into the future. Unless the past is dealt with, it becomes a haunting memory that saps the strength of the believer so he is unable to honor Christ in his daily life.
What God does with sin when it is confessed is explained in various passages.Isaiah 44:22 says, "I have wiped out your transgressions like a thick cloud, and your sins like a heavy mist. Return to Me, for I have redeemed you" (NASB).
Hebrews 8:12 says, "FOR I WILL BE MERCIFUL TO THEIR INIQUITIES, AND I WILL REMEMBER THEIR SINS NO MORE" (NASB).
Someone has said, "The present must forget the past by correction, or else the past will become a moral and spiritual liability for the future."
Consider some items that need to be forgotten: failures--they keep our faith from advancing; successes--they create pride (see Prov. 16:18); losses--they drag us down so we cannot serve the Lord the way we should; grievances--they produce false attitudes (see 1 Cor. 13:6); sorrows--God can heal all heartaches; discouragements--we need to remember Christ, not disappointments, thwarted hopes and plans.
"And their sins and iniquities will I remember no more" (Heb. 10:17).