Isaiah 43:25

I, I am the one who blots out your rebellious deeds for my sake; your sins I do not remember.

Earlier, in verses 14-15, the speaker calls Himself, "The Lord, your Holy One, Israel's creator and King." It is not by our own power, but by the power of God in Christ Jesus: that is the power that blots out our sins. It is the blood of the Lamb! This promise rings throughout scripture: that God's design for us was always to redeem us to Himself and reconcile our broken relationship. Sin broke our relationship with God in the garden of Eden. Jesus Christ restores that relationship, and allows us to receive His grace and forgiveness of sins. When God looks on believers in Christ He sees His perfect Son standing in the breech. Jesus' righteousness is credited to us; sinners in desperate need of a Savior.