“Sing, O barren, thou that didst not bear; break forth into singing, and cry aloud, thou that didst not travail with child: for more are the children of the desolate than the children of the married wife, saith the LORD.” — Isaiah 54:1
The arc of Israel’s narrative in redemptive history in many ways presents an allegory of our own individual conversion. Of our own selves we are barren and destitute of any merit. Throughout the scriptures children are described as a blessing and a reward from the Lord, which comes with it the presumption that infertility must also correlate with sin and failure. Many a woman in the Old Testament poured out their complaint before the Lord to be relieved of the reproach of barrenness. The Lord was pleased to deliver each of them in due time, even those that were well past childbearing age (for with God nothing shall be impossible) [1].
But how can the desolate have more children than the married wife? By the gospel of our faith which is not of the flesh but of the spirit. Paul calls Timothy his "own son in the faith" and Onesimus as someone, “whom I have begotten in my bonds. [2]” The Bible is not saying that men get pregnant. It is saying that through the foolishness of preaching[3] Paul has become a spiritual parent to a burgeoning believer. Galatians 5:27 says,
But Jerusalem which is above is free, which is the mother of us all.
Selah.