And their sins and iniquities will I remember no more (Hebrews 10:17).
In contrast to the Old Testaments yearly remembrance of sin, the New Testament believers sin is forever forgotten. This is due to the shed blood of Christ who entered into the holiest of all to make a perfect atonement for us.
There are a number of descriptive phrases in Scripture to show just how completely God has done away with those sins that once plagued us. They are as follows: Isaiah 44:22: I have blotted out, as a thick cloud, thy transgressions, and, as a cloud, thy sins: return unto me; for I have redeemed thee. Sins are compared to clouds in that there are a large number of them; they cause darkness; they completely obscure heaven; they come between heaven (God) and earth (man), and they are a sign of an impending storm (judgment). Yet now, in Christ, those sins that separated us from God have once and for all been blotted out. Psalm 103:12: As far as the east is from the west, so far hath He removed our transgressions from us. Because of Christ, we will never meet up with our sin again. Micah 7:19: He will subdue our iniquities; and cast all their sins into the depths of the sea. Iniquity has been conquered (subdued) and sin hurled (cast) into the deepest sea. It is destroyed, lost, and irrecoverable! Isaiah 38:17: But thou hast in love to my soul delivered it from the pit of corruption: for thou hast cast all my sins behind thy back. God hurls sin behind His back because it is abominable and loathsome. He will never look at it again. He has completely separated Himself from it.
The reason why all of this is true is found in II Corinthians 5:21, For He hath made Him (Christ) to be sin for us, who knew no sin; that we might be made the righteousness of God in Him. NPS