2. If you keep in memory — unless in vain (9) These two expressions are very cutting. In the first, he reproves their carelessness or fickleness, because such a sudden fall was an evidence that they had never understood what had been delivered to them, or that their knowledge of it had been loose and floating, inasmuch as it had so quickly vanished. By the second, he warns them that they had needlessly and uselessly professed allegiance to Christ, if they did not hold fast this main doctrine. (10)
(9) “Our version does not express intelligibly the sense of ἐκτὸς εἰ μὴ εἰκὢ ἐπιστεύσατε by rendering it so literally — unless ye have believed in vain. To believe in vain, according to the use of ancient languages, is to believe without just reason and authority, giving credit to idle reports as true and authentic. Thus Plutarch, speaking of some story which passed current, says, τοῦτο ἡμεῖς ἐ᾿ἴπομεν ἐν τί τῶν εἰκὢ πεπιστεύμενων — “this I said was one of those tales which are believed without any good authority.” (Sympos. lib. 1, quaest. 6.) The Latins used credere frustra — to believe in vain, or temere — (rashly.) Kypke takes notice that ἐκτὸς εἰ μὴ, for except or unless, which has long been a suspected phrase, is used more than ten times by Lucian. It is also used by Plutarch in the Life of Demosthenes, volume 4.” — Alexander’s Paraphrase on 1 Corinthians 15. (London, 1766,) — Ed.
(10) “ Ce principal poinct de la foy ; ” — “This main article of faith.”