Hebrews 8:12

For I will be merciful to their unrighteousness, and their sins and their iniquities will I remember no more.

God promises under the new covenant to show tender, abundant mercy by forgiving unrighteousness and never again holding fully confessed and forgiven sins and iniquities against the sinner.
The promise belongs to those who turn to God, humble themselves, confess and forsake sin, and come to Christ in faith, and they receive pardon through His blood, grace, and assurance of salvation.
Christ Himself pleads this promise with the Father for believers, asking Him not to charge their sins to them but to lay them upon Himself.
This mercy does not set justice aside or leave sin unpunished, for perfect obedience remains the condition of life and Christ's sacrifice, merits, and blood meet and satisfy the law's demands for every repentant, believing sinner.
In the judgment, when each record is examined, Jesus confesses the name of the penitent, God-fearing soul before the Father, his name is kept in the book of life and his fully repented sins are held against him no longer, while unrepented sins stand against the sinner and cause his name to be blotted out.
Those who have confessed all to God should therefore trust the pledge, believe they are pardoned, and live free in Christ rather than in remorse, with the Holy Spirit renewing their minds unto holiness.

The Covenant Promise

The verse gives the blessing of the new covenant as God's tender and abundant mercy, in which He forgives unrighteousness and no longer holds sins and iniquities against the sinner. That pardon through His tender mercy is salvation for the repentant sinner. It is for those who turn to Him, forsake evil and choose good, humble themselves, confess and forsake sin, and come to Christ in faith. To them He grants mercy, grace, pardon through His blood, and assurance.

To remember no more means that fully confessed and forgiven sins and iniquities are no longer held against the sinner. God gives His pledged word never to bring them up again and wipes wrongdoing from memory. So the sinner is free in Christ Jesus. Because of Christ, God forgets the sinner's sins and remembers the sinner's needs.

The mercy and forgiveness of the new covenant includes the white people and the colored people of the Southern States. They have souls to save and must not be passed by. They must be taught that Christ is their Creator and Redeemer.

Christ's Mediation and Justice

The verse is the voice of Christ pleading with the Father on behalf of believers, asking Him not to charge their sins to them but to lay those sins upon Himself, to be merciful to their unrighteousness and to remember their sins and iniquities no more. He bears their sins Himself so that full pardon wipes all wrongdoing from memory. This intercession fulfills the plan of salvation devised in infinite love and arranged in the counsels between the Father and the Son, in which Christ pledged Himself to render an account for man if he proved disloyal and to make an atonement that would unite every believing soul to God.

It is spoken in behalf of all who will cooperate with Him by laying their sins upon the Substitute and Surety, accepting His merits, making peace with Him, and becoming partakers of the divine nature. For those who believe, His righteousness becomes theirs and His righteous merit is counted as theirs. They are united to God, they have peace and rest, and for His sake they are blessed in Him with all spiritual blessings and with every spiritual blessing.

This mercy does not set aside justice, make God unjust, or allow sin to go unpunished or the law to be transgressed without consequence. Perfect obedience remains the condition of life under the covenant. Christ's sacrifice secures forgiveness by satisfying the law's demands, and He fulfills the law for transgressors who receive Him, so that every repentant, believing sinner who humbles himself, confesses sin, turns from evil, and comes to Christ in faith receives pardon, mercy, grace, cleansing, and assurance through His merits and blood, since sinners cannot atone for their own sins.

In the investigative judgment, when the names written in the Lamb's book of life are called and each record is examined by Him who knows works, temptations, circumstances, weaknesses, and infirmities, Jesus pleads for the poor penitent, self-distrustful, God-fearing soul harassed with doubts and temptations and confesses his name before the Father and the holy angels. The Father pities him, his name is not blotted from the book of life, and God holds his fully repented sins and wicked deeds against him no longer. By contrast, if wicked deeds have not been fully repented of, or the professed believer becomes self-confident and breaks even the least precept of God's holy law and misrepresents Jesus, his name is blotted from the book of life and his sins stand against him.

Trusting and Living Forgiven

When all transgressions have been confessed to God and pardon has been asked, the promise is to be trusted and acted upon by believing that pardon is given. God gives His pledged word to pardon and never to bring forgiven sins up again, for He pardons transgressions and remembers forgiven sins and iniquities no more. The sinner is therefore to live free in Christ Jesus rather than remaining in remorse. Keen remorse and sorrow over the past give way to assurance, freedom, and looking to Christ and living.

God is merciful toward those who confess and forsake unrighteousness, forgiving their sins and iniquities and remembering them no more, and those who repent and come to Christ in faith receive pardon through His blood. The Holy Spirit leads the repentant to Christ and renews their minds unto holiness. Those who have acted in a wrong, unchristian spirit must confess that spirit and, as far as lies in their power, remove the false impression they left on other minds that misrepresented their brethren. Jesus loves one who has yielded to temptation and confessed it more dearly than if there had been no error and no breach in the armor.