John Calvin Commentary Isaiah 54:6

"For Jehovah hath called thee as a wife forsaken and grieved in spirit, even a wife of youth, when she is cast off, saith thy God." — Isaiah 54:6 (ASV)

For as a woman forsaken. He addresses a doubt that might arise in the minds of believers amidst such a distressing calamity. It seemed as if the Lord had rejected them, so that they had nothing to look for but destruction. The Prophet therefore reminds them that they ought not to despair, because they have been so forsaken; for God, according to his mercy, is ready to be reconciled, and is even willing to raise them from the dead.

And a wife of youth. He employs this expression so that, by this metaphor, he may more fully confirm their hearts in that hope; for the hearts of young husbands are more easily reconciled than the hearts of older husbands, being attracted, and, as it were, driven forward by youthful age and tender love. Similarly, he shows that God will be easily reconciled. “True, you were divorced; but the divorce shall not be of long duration. The Lord will show himself ready to be reconciled, and will even, of his own accord, be the first to invite you to reconciliation.”