In a recent article in First Things entitled 'Why Study Biblical Languages' Nicholas Frankovich offers an account of the dialogue between Jesus and Peter in John 21.15-17 in ways that will be familiar to anyone who has listened to sermons on this text. He writes:
For Christians, the most familiar locus classicus for the value of reading the New Testament in Greek comes toward the end of the Gospel according to John, just before the part where Peter points to John and asks Jesus, in effect, “So what great things do you have in store for him?” Peter sounds envious. Why Jesus’ rapport with John was so much greater is suggested by the passage leading up to this hint of a rivalry between Peter, the disciple whom Jesus appointed to the position of highest authority, and John, “the disciple whom Jesus loved” or, as we might say, counted as his closest friend, perhaps because John appreciated certain qualities of his mind that were lost on the others.
Jesus had asked Peter three times whether Peter loved him. The first two times, Peter replied, “Of course, Lord, you know I love you.” The third time, he replied with the same answer but now added a note of slight indignation that Jesus was repeating himself. Most translators don’t even try to convey the distinction between the two words for the two different kinds of love that are in play here.
Now consider the whole exchange again in light of what in the Greek defies easy translation into English. Jesus asks Peter, “Do you agapas me?” Peter replies, “Lord, you know I phil you.” Jesus tries again and gets the same result. So what does he do? He decides to be tactful. Conceding to Peter’s vocabulary, he now asks him, “Do you phileis me?” John writes that Peter was upset that Jesus was asking him “Do you phileis me?” yet a third time. The suggestion is that Peter was deaf to the difference between the two words, that he wasn’t sensitive to the subtle but significant distinction—and that Jesus, whose tongue was famously sharp and his wit quick, out of kindness deferred to his friend’s blunter intellect, as a father when talking to his child will sometimes adopt the child’s language.
Sound familiar? The thing is that one of the main reasons why I would suggest anyone should learn New Testament Greek is so that they can see this kind of interpretative hogwash for what it is. Leaving aside the all too easy assumption that Jesus and Peter had a real conversation in Greek (and not Aramaic), I would simply state the considered view of Raymond Brown:
[t]he present writer is forced to align himself with scholars ancient (the OL translators, Augustine) and modem (Lagrange, Bernard, Moffatt, Strachan, Bonsirven, Bultmann, Barrett, etc.) who find no clear distinction of meaning in the alternation of agapan and philein in vss. 15-17. The reasons for this are: (a) There seems to be a general interchangeability of the two verbs in John; see vol. 29, p.498; also Bernard. II. 702-4. (b) In Hebrew and Aramaic there is one basic verb for expressing the various types of love, so that all the subtlety of distinction that commentators find in the use of the two verbs in 1S-17 scarcely echoes the putative Semitic original. We note that LXX uses both verbs to translate Heb. aheb, although agapan is twenty times more frequent than philein. In the Syriac translations of 15-17 only one verb is used. (c) Peter answers "Yes" to the questions phrased with the verb agapan even though he expresses his love in terms of philein and thus shows no awareness that he is answering a request for a higher or more spiritual or more rationaltype of love (agapan) with an offer of a lower or more affectionate form of love (philein). (The Gospel According to John XIII-XX1: AB 29A; New York: Doubleday, 1970), 1103.
Learning New Testament Greek is not just a tool for seeing new things in the text, it is a tool for beginning to see why many of the things you have been taught to see might actually be bad interpretations.