ταῦτ' ἂν εἴη βλαβερά

From LSJ

τὰ καλὰ καὶ συμφέροντα ταῖς ψυχαῖς ἡμῶν καὶ εἰρήνην τῷ κόσμῳ → what is good and profitable to our souls, and for peace to the world

Source

Greek > English (Woodhouse)

these doctrines must be harmful