a1 Caius College, Cambridge, England
It seems agreed that κερδαίνω in the sense of ‘to win over an unbeliever to one's faith’ (I Cor. 9.19–22, I Pet. 3.1) or ‘to win back a sinner to the way of life required by his and your faith’ (Matt. 18.15) is an echter terminus technicus der Missions-sprache; by which is meant, apparently, that there is no precedent for this sense of the word in either Hellenistic or Rabbinic language. I wish to suggest that this view is not correct; and that the use of κερδαίνω in the passages in question, while conceivably reflecting a specifically Christian trend, is in the main determined by the Rabbinic vocabulary.
1 Read in Professor C. H. Dodd's Seminar on the New Testament at Cambridge.