Isaiah 54:4 (ESV) … “Fear not, for you will not be ashamed; be not confounded, for you will not be disgraced; for you will forget the shame of your youth, and the reproach of your widowhood you will remember no more.”
A wife reconciled to her husband is Isaiah’s second image of miraculous grace. The striking thing is what the text doesn’t say. The faithful city had sunk to the level of a whore (Isaiah 1:21). But now God looks beyond his people’s guilt. He doesn’t even talk about it. With deep sympathy, he emphasizes not his offended honor but their wounded feelings: “… like a wife left and grieved in spirit, like a wife of youth when she is cast off.” God is saying, “Yes, I was angry. And I had a right to be. But my servant has taken your guilt away. Believe me that I have cleaned your slate so entirely, you will forget all your heartache under a deluge of my felt love forever.”
The gospel is not “He loves me, he loves me not,” depending on our own loveliness. The grace of God is a “covenant of peace” (Isaiah 54:10), a permanent arrangement bringing us a wholeness we don’t deserve. Therefore, we can enjoy God’s grace without fearing that he’ll retract it (54:4). We didn’t cause his grace to begin with, so we can’t reverse it now. God’s anger is real, but passing. His love is also real, and lasting—forever. God is the ultimate romantic (“everlasting love”). For all spiritual whores who will receive it, this is God’s word. Break forth into singing and cry aloud! 
As a loving husband who has married a bride with a shameful and sad past, the Lord will remain committed to Israel as his undeserving but beloved wife. This commitment is based on a covenant as lasting as the one the Lord made with Noah and more solid than the mountains (54:9–10). It is a covenant of peace, ensuring the end of anger and the enjoyment of a love that knows no end.