SOURCE: Tolle Lege
“The nature of forgiveness will more clearly appear by opening some Scripture-phrases.
1. To forgive sin, is to take away iniquity. ‘Why dost thou not take away my iniquity?’ (Job 7:21). It is a metaphor taken from a man that carries an heavy burden ready to sink him, and another comes, and lifts off this burden. So when the heavy burden of sin is on us, God in pardoning, lifts off this burden from the conscience, and lays it upon Christ: ‘The Lord hath laid on him the iniquities of us all’ (Isa. 53:6).
2. To forgive sin, is to cover sin. ‘Thou hast covered all their sin,’ (Ps. 32:1). This was typified by the mercy-seat covering the ark, to show God’s covering of sin through Christ. God doth not cover sin in the Antinomian sense, so as He sees it not, but He doth so cover it, as He will not impute it.
3. To forgive sin, is to blot it out. ‘I am he that blotteth out thy transgressions,’ (Isa. 43:25). The Hebrew word, to lot out, alludes to a creditor, who, when his debtor hath paid him, blots out the debt, and gives him an acquittance. So God, when He forgives sin, blots out the debt, He draws the red lines of Christ’s blood over our sins, and so crosseth the debt-book.
4. To forgive sin, is for God to scatter our sins as a cloud. ‘I have blotted out as a thick cloud thy transgressions,’ (Isa. 44:22). Sin is the cloud interposed, God dispels the cloud, and breaks forth with the light of His countenance.
5. To forgive sin, is for God to cast our sins into the depths of the sea. ‘Thou wilt cast all their sins into the depths of the sea,” (Micah 7:19). This implies God’s burying them out of sight, that they shall not rise up in judgment against us. God will throw them in, not as cork that riseth again, but as lead that sinks to the bottom.”
–Thomas Watson, The Lord’s Prayer (Carlisle, PA: Banner of Truth Trust, 1662/1999), 214-215.