The barren church now fruitful
The preacher is applying Isaiah's words about the barren woman to the church, which was once barren but now has many children through faith.
"Rejoice, barren one who bears no children; break forth and shout, you who are not in labor, for the children of the desolate one are more numerous than the children of her who has a husband" (Isaiah 54:1). When he said, "Rejoice, barren one who bears no children," he was speaking about us. For our church was barren before children were given to her.
And when he said, "Shout, you who are not in labor," this is what he means: we should offer up our prayers to God simply, and not grow weary as women in labor do.
And when he said, "For the children of the desolate one are more numerous than the children of her who has a husband," he said this because our people once seemed desolate, abandoned by God. But now that we have believed, we have become more numerous than those who seemed to have God.
And another scripture says, "I did not come to call the righteous, but sinners" (Matthew 9:13). This means that he must save those who are perishing. For the great and wonderful thing is not to support what is standing, but what is falling. So also Christ willed to save the things that were perishing, and he saved many, coming and calling us when we were already perishing.
Greek
Εὐφράνθητι, στείρα ἦ οὐ τίκτουσα, ῥῆξον καὶ βόησον, ἡ οὐκ ὠδίνουσα, ὅτι πολλὰ τὰ τέκνα τῆς ἐρήμου μᾶλλον ἢ τῆς ἐχούσης τὸν ἄνδρα. ὃ εἶπεν: Εὐφράνθητι, στεῖρα ἡ οὐ τίκτουσα, ἡμᾶς εἶπεν: στεῖρα γὰρ ἦν ἡ ἐκκλησία ἡμῶν πρὸ τοῦ δοθῆναι αὐτῇ τέκνα.
ὃ δὲ εἶπεν: Βόησον, ἡ οὐκ ὠδίνουσα, τοῦτο λέγει: τὰς προσευχὰς ἡμῶν ἁπλῶς ἀναφέρειν πρὸς τὸν θεόν. μὴ ὡς αἱ ὠδίνουσαι ἐγκακῶμεν,
δ δὲ εἶπεν: Ὅτι πολλὰ τὰ τέκνα τῆς ἐρήμου μᾶλλον ἢ τῆς ἐχούσης τὸν ἄνδρα: ἐπεὶ ἔρημος ἐδόκει εἶναι ἀπὸ τοῦ θεοῦ ὁ λαὸς ἡμῶν. νυνὶ δὲ πιστεύσαντες πλείονες ἐγενόμεθα τῶν δοκούντων ἔχειν θεόν.
καὶ ἑτέρα δὲ γραφὴ λέγει, ὅτι οὐκ ἦλθον καλέσαι δικαίους, ἀλλὰ ἁμαρτωλούς:
τοῦτο λέγει, ὅτι δεῖ τοὺς ἀπολλυμένους σώζειν.
ἐκεῖνο γάρ ἐστιν μέγα καὶ θαυμαστὸν οὐ τὰ ἑστῶτα στηρίζειν, ἀλλὰ τὰ πίπτοντα.
οὕτως καὶ ὁ Χριστὸς ἠθέλησεν σῶσαι τὰ ἀπολλύμενα, καὶ ἔσωσεν πολλούς, ἐλθὼν καὶ καλέσας ἡμᾶς ἤδη ἀπολλυμένους.