Sects show who is approved
If this reasoning holds, why should we not make the same defence for the sects among Christians as well? Of these, Paul seems to me to have spoken most admirably: “For there must also be sects among you, so that those who are approved may become manifest among you” (1 Corinthians 11:19). For the man approved in medicine is the one who, having trained himself in various sects and fairly examined most of them, has chosen the best; and the man who makes great progress in philosophy is the one who, having come to know more of them, has trained himself in them and attached himself to the argument that prevailed. In the same way I would say that one who has looked carefully into the sects of Judaism and of Christianity becomes a most wise Christian.
But anyone who accuses the word because of the sects would also accuse the teaching of Socrates, from whose school there have come many schools of men who do not think alike. One might also accuse Plato’s doctrines because of Aristotle, who broke away from his school by introducing new ideas; we have spoken of him earlier too.
Celsus, it seems to me, knew of some sects that do not even share the name of Jesus with us. Perhaps he had heard talk of the so-called Ophites and Cainites, and of any other such school of thought that has arisen by breaking away from Jesus entirely. But this does nothing to show that the teaching of Christians is open to accusation.
Greek
Εἰ δὲ ταῦτ᾿ ἔχει ἀκολουθίαν, πῶς οὐχὶ ὁμοίως ἀπολογησόμεθα καὶ περὶ τῶν ἐν Χριστιανοῖς αἱρέσεων; περὶ ὧν πάνυ θαυμασίως ὁ Παῦλος εἰρηκέναι μοι δοκεῖ τό· „δεῖ γὰρ καὶ αἱρέσεις ἐν ὑμῖν εἶναι, ἵνα οἱ δόκιμοι φανεροὶ γένωνται (ἐν ὑμῖν) .“ ὡς γὰρ δόκιμος ἐν ἰατρικῇ ὁ διὰ τὸ γυμνάσασθαι ἐν ποικίλαις αἱρέσεσι καὶ εὐγνωμόνως ἐξητακέναι τὰς πλείονας ἑλόμενος τὴν διαφέρουσαν, καὶ ὡς ὁ πάνυ προκόπτων ἐν φιλοσοφίᾳ ἀπὸ τοῦ πλείονα ἐγνωκέναι ἐγγυμνασάμενος αὐτοῖς καὶ τῷ κρατήσαντι προσθέμενος λόγῳ· οὕτως εἴποιμ᾿ ἂν καὶ τὸν ἐπιμελῶς ἐνιδόντα ταῖς ἰουδαϊσμοῦ καὶ χριστιανισμοῦ αἱρέσεσι σοφώτατον Χριστιανὸν γενέσθαι. ὁ δ᾿ ἐγκαλῶν τῷ λόγῳ διὰ τὰς αἱρέσεις ἐγκαλέσαι ἂν καὶ τῇ Σωκράτους διδασκαλίᾳ, ἀφ᾿ οὗ τῆς διατριβῆς πολλαὶ γεγόνασιν οὐ τὰ αὐτὰ φρονούντων σχολαί· ἀλλὰ καὶ Πλάτωνος ἐγκαλέσαι ἄν τις τοῖς δόγμασι δι᾿ Ἀριστοτέλην, ἀποφοιτήσαντα τῆς διατριβῆς αὐτοῦ ἐν καινοτομίαις· περὶ οὗ καὶ ἐν τοῖς ἀνωτέρω εἰρήκαμεν. δοκεῖ δέ μοι ὁ Κέλσος ἐγνωκέναι τινὰς αἱρέσεις μηδὲ τοῦ ὀνόματος τοῦ Ἰησοῦ κοινωνούσας ἡμῖν. τάχα γὰρ περιήχητο περὶ τῶν καλουμένων Ὀφιανῶν καὶ τῶν Καϊανῶν, καὶ εἴ τις ἄλλη τοιαύτη ἐξ ὅλων ἀποφοιτήσασα τοῦ Ἰησοῦ συνέστη γνώμη· πλὴν οὐδὲν τοῦτο πρὸς τὸ ἐγκλητέον εἶναι τὸν Χριστιανῶν λόγον.