How do we know that Christ will produce children through the gospel?

Scripture teaches that the church, as Christ's bride, is tasked with preaching the gospel, which is the means by which Christ will produce spiritual children. Isaiah 54:1-2 states, 'Sing, O barren, thou that didst not bear; break forth into singing, and cry aloud.' This command not only highlights the joy that comes from knowing Christ but also affirms His promise to generate spiritual fruit through the faithful proclamation of the gospel. The parable of the sower in the Gospels also illustrates this, where the seed (the word of God) is sown and results in a fruitful harvest, emphasizing that Christ, through His church, will effectively reach His elect and create a new life in them. The apostle Paul affirms this in Galatians 4:26, where he states, 'But Jerusalem which is above is free, which is the mother of us all.'