There may be several reasons why your past is still ‘haunting’ you.  If you have sinned against someone, it is important that you go to that person and confess that sin to him/her.  The Lord instructs us in Matthew 5:23-24, “Therefore if thou bring thy gift to the altar, and there rememberest that thy brother hath ought against thee; Leave there thy gift before the altar, and go thy way; first BE RECONCILED TO THY BROTHER, and then come and offer thy gift.”  The Lord was pointing out how that reconciliation with an offended person could interfere with our proper worship of the Lord.  To truly worship our Lord, we should approach Him with a repentant heart.

Perhaps you have not confessed your sin to the Lord.  It is true repentance to the Lord that will lead us to repent to our brother or sister in Christ.  True repentance has such a cleansing effect upon us.  We read in 1 John 1:9, “If we confess our sins, he is faithful and just to forgive us our sins, and to cleanse us from all unrighteousness.”  When we confess our sins to the Lord, He not only FORGIVES us of that sin but He also CLEANSES us of that sin.  Because of that cleansing, we can have a clean conscience before the Lord and it will prompt us to reconcile with the one we have offended or sinned against.

There could be another reason why you are still being haunted by your past.  Perhaps the Lord has forgiven you, but you have not been able to forgive yourself.  Sometimes we just don’t realize the power of forgiveness.  Even after confessing to the Lord and confessing to the one we sinned against, we might find that we just cannot put that behind us and move forward.  If that is the case, I encourage you to consider the cleansing impact that comes with confessing to the Lord.  Allow that cleansing to help you let go of the sins that have already been confessed, forgiven, and cleansed.

I hope that I have answered your question clearly and completely enough for you to take the proper actions and put this matter to rest.  You cannot effectively serve the Lord in the state you are in right now, so do that which is scripturally appropriate.  I believe your question indicates that you want to do what is necessary.  May the Lord guide you in a path of obedience to His will.  (353.2)