When we repent, Jesus Christ blots out our sins and remembers them no more.
Isaiah 43:25–26; 44:21–23
25 I, even I, am he that blotteth out thy transgressions for mine own sake, and will not remember thy sins.
26 Put me in remembrance: let us plead together: declare thou, that thou mayest be justified. . . .
21 Remember these, O Jacob and Israel; for thou art my servant: I have formed thee; thou art my servant: O Israel, thou shalt not be forgotten of me.
22 I have blotted out, as a thick cloud, thy transgressions, and, as a cloud, thy sins: return unto me; for I have redeemed thee.
23 Sing, O ye heavens; for the Lord hath done it: shout, ye lower parts of the earth: break forth into singing, ye mountains, O forest, and every tree therein: for the Lord hath redeemed Jacob, and glorified himself in Israel.
President Boyd K. Packer said:
“Forgiveness from the Lord is earned through great personal effort. It takes courage to face the reality of your transgression, accept whatever penalty is required, and allow sufficient time for the process to work. When that is done, you will be innocent again. The Lord said: ‘I, even I, am he that blotteth out thy transgressions for mine own sake, and will not remember thy sins’ (Isaiah 43:25). . . .
“There is the idea abroad that one can send a postcard of prayer and receive in return full forgiveness and be ready at once for a mission or for marriage in the temple. Not so; there are payments to be made. If a bishop offers comfort only and, in misguided kindness, seeks to relieve you of the painful but healing process in connection with repentance, he will not serve you well.”
(The Things of the Soul , 116, 115–16.)