Mercy is at the heart of this covenant, for our sin is a reality which will not go away on its own. The verse refers to all three of the categories of sinner here. ‘Merciful to their unrighteousness,’ – that is their disobedience, ‘and to their sins,’ – to their actual individual missing-of-the-mark sins, ‘and their iniquities’ – literally, their twistedness, their perversion. God does not forgive us by pretending sin does not exist, but by purging it away through the cross. When we consider where our sins ought to have taken us, and what is the condition of those who have not been shown mercy, we understand better the value of our forgiveness. Will those in hell ever cease calling on God to send them relief? However long they cry his ears will be closed to them, and his wrath towards them will relentlessly continue, and forgiveness will never be extended to them. As far as they are concerned the will of God is unchangeable. And yet, wonder of wonders, his ear has been open to our cries, and we have prevailed with him in prayer; mercy has been shown to us, and God has had compassion on us. What could we have done to bring this about? Well certainly, we have called on the name of the Lord, but God did not begin to love us because of that. We have understood our great need and come to him for mercy, but that is only as a result of his drawing us to himself because he secretly loved us from before the foundation of the world. We have no control over the secret will of God. He has responded to our cries and they have obtained what the cries of those in hell will never obtain, but that is the mystery of his electing love.
God has given us a covenant which he himself has scrutinised for any fault or weakness. Thanks be to God that he has not left in place the weak and beggarly elements of the law (Galatians 4:9), but has in the fulness of time shown us the full scope of grace through the redemptive work of Christ. We can now place full confidence in that covenant, knowing that it is sufficient to save us for all eternity, and that there is no agent in heaven or earth or hell that can point to any flaw in it, or separate us from the love of God which is in Christ Jesus our Lord.
How can God really forget anything? How can he blot out what I have done? It is like the law of the land. The judge may not forget what has happened but, if I am acquitted, the system forgets. Of course he does not forget the case that has come before him, but he puts it out of mind in this sense. So too the law of God ceases to accuse us.