Galatians 4:27 For it is written, Rejoice, thou barren that bearest not; break forth and cry, thou that travailest not: for the desolate hath many more children than she which hath an husband.
For it is written; 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 Church of God under the Old Testament, confined within the narrow bounds of the Jewish nation, and still more so in respect of the very small number of true believers, and which sometimes seemed to be deserted of God her husband, is the barren woman, that did not bear, and was desolate. She is exhorted to rejoice, and to express her joy in the strongest manner, on the reconciliation of her husband, (see Isaiah_54:6), and on the accession of the Gentiles to her family. The reason to rejoice is there is an explosion of Grace to burst upon the world of the gentiles. What an amazing verse and revelation from God. The converted Gentiles are all along considered by the prophet as a new accession of adopted children, admitted into the original Church of God, and united with it. The Church of God under the Old Testament, confined within the narrow bounds of the Jewish nation, and still in its new born state, with few born again Jewish Christians is in the process of adopting gentiles into the family of God. True believers in the Jewish Church should rejoice at this revelations that God was grafting in the gentiles. But there was trouble makers as we read in the prior verses, that was having nothing to do with this. And when the Gentiles heard this, they were glad, and glorified the word of the Lord: and as many as were ordained to eternal life believed. (Acts 13:48)
Sarah who was of the (Promise) was barren, Hagar who was of the Law was very fertile and could bear many children, Sarah who was barren felt neglected of God, now Sarah represents the (Promise) which every Gentile is blessed by that promise. The gentile being fatherless and felt just as neglected be aliens in the common wealth of God. What I am trying to say is that our rich Christian heritage started with the barren Sarah the (Promise) Therefore; “Praise, O Jerusalem, which was as a barren woman that bringeth not forth; rejoice in praise, and be glad, who was as a woman which conceives not, for more are the children of Jerusalem forsaken than the children of the habitable city, saith the Lord.”