The sheep that are not in this sheep pen is taken by most commentators as a reference to Gentile believers. However, this is not the kind of information which a translator should introduce into the text.

As Good News Translation points out in footnote “v,” they will become one flock with one shepherd reads in some manuscripts “there will be one flock with one shepherd.” There is strong Greek manuscript evidence for each of these readings, but “they will be” has slightly stronger support. The UBS Committee on the Greek text judges that “there will be” was introduced as a stylistic correction. It should at least be pointed out that most modern English translators favor “there will be.” In fact, Good News Translation is definitely in the minority with its reading they will become. Fortunately, as far as ultimate meaning is concerned, there is no basic difference.

They will become one flock implies that the other sheep, as well as those of the sheep pen of which Jesus is speaking, will together become one flock. It may therefore be necessary to say in some languages “they all will become one flock,” since they must refer both to the sheep within the sheep pen and to the other sheep.

With one shepherd may be expressed as a separate clause, for example, “they will become one flock and they will have one shepherd” or “… and one shepherd will take care of them.”

Quoted with permission from Newman, Barclay M. and Nida, Eugene A. A Handbook on the Gospel of John. (UBS Handbook Series). New York: UBS, 1980. For this and other handbooks for translators see here .