Genesis says nothing of God repenting
Next we must answer this: “How does He repent over them when they have become ungrateful and wicked, and find fault with His own art, and hate, and threaten, and destroy His own offspring?” Here he slanders and misrepresents what is written in Genesis, which runs as follows: “When the Lord God saw that the wickednesses of those on the earth had multiplied, and that everyone was intently planning evil things in his heart all the days, God took it to heart that He had made man on the earth. And He considered it in His heart, and God said: I will wipe out man, whom I made, from the face of the earth, from man to beast, and from creeping things to the birds of the sky; for I am angry that I made them” (Genesis 6:5–7). He sets out what is not written as if it were made plain by what is written. For in these words no repentance of God is named, nor is it said that He finds fault with His own art and hates it.
But if God seems to threaten the flood, and in it to destroy His own offspring, we must say that, since the soul of men is immortal, the supposed threat is meant to turn the hearers back, while the destruction of men in the flood is a cleansing of the earth. So too those Greeks whose philosophy is not to be despised have said, in the words: “But when the gods cleanse the earth” (Plato, Timaeus 22d). As for the expressions that ascribe, as it were, human passions to God, we have said a good deal about them in the earlier parts as well.
Greek
Εἶθ᾿ ἑξῆς ἐστιν ἀπαντῆσαι πρὸς τὸ πῶς δ᾿ ἐπ᾿ αὐτοῖς ἀχαρίστοις καὶ πονηροῖς γενομένοις μεταμέλει καὶ τὴν ἑαυτοῦ τέχνην μέμφεται καὶ μισεῖ καὶ ἀπειλεῖ καὶ φθείρει τὰ ἴδια ἔκγονα; συκοφαντεῖ δ᾿ ἐν τούτοις καὶ καταψεύδεται τῶν ἐν τῇ Γενέσει γεγραμμένων τὸν τρόπον τοῦτον· „ἰδὼν δὲ κύριος ὁ θεὸς ὅτι ἐπληθύνθησαν αἱ κακίαι τῶν ἐπὶ τῆς γῆς, καὶ πᾶς τις διανοεῖται ἐν τῇ καρδίᾳ ἐπιμελῶς ἐπὶ τὰ πονηρὰ πάσας τὰς ἡμέρας, ἐνεθυμήθη ὁ θεὸς ὅτι ἐποίησε τὸν ἄνθρωπον ἐπὶ τῆς γῆς· καὶ διενοήθη ἐν τῇ καρδίᾳ αὐτοῦ καὶ εἶπεν ὁ θεός· ἀπαλείψω τὸν ἄνθρωπον, ὃν ἐποίησα, ἀπὸ προσώπου τῆς γῆς, ἀπὸ ἀνθρώπου ἕως κτήνους καὶ ἀπὸ ἑρπετῶν ἕως τῶν πετεινῶν τοῦ οὐρανοῦ· ὅτι ἐθυμώθην, ὅτι ἐποίησα αὐτοὺς,“ τὰ μὴ γεγραμμένα ἐκτιθέμενος ὡς δηλούμενα ἀπὸ τῶν γεγραμμένων. μεταμέλεια γὰρ ἐν τούτοις οὐκ ὠνομάσθη θεοῦ οὐδ᾿ ὅτι τὴν ἑαυτοῦ τέχνην μέμφεται καὶ μισεῖ. εἰ δὲ δοκεῖ ὁ θεὸς ἀπειλεῖν τὰ τοῦ κατακλυσμοῦ καὶ φθείρειν ἐν αὐτῷ τὰ ἴδια ἔκγονα, λεκτέον ὅτι, ἀθανάτου τῆς ψυχῆς τῶν ἀνθρώπων τυγχανούσης, ἡ μὲν νομιζομένη ἀπειλὴ ἐπιστρέφειν βούλεται τοὺς ἀκούοντας, ἡ δ᾿ ἐν τῷ κατακλυσμῷ διαφθορὰ τῶν ἀνθρώπων καθάρσιόν ἐστι τῆς γῆς, ὡς καὶ Ἑλλήνων οἱ μὴ εὐκαταφρονήτως φιλοσοφήσαντες εἰρήκασιν ἐν τῷ· „ὅταν δ᾿ οἱ θεοὶ τὴν γῆν καθαίρωσι.“ περὶ δὲ τῶν ὡσπερεὶ ἀνθρωποπαθῶν λέξεων ἀναφερομένων ἐπὶ τὸν θεὸν οὐκ ὀλίγα ἡμῖν καὶ ἐν τοῖς ἀνωτέρω λέλεκται.