“And other sheep I have, which are not of this fold: them also I must bring, and they shall hear my voice; and there shall be one fold, and one shepherd.”
I have other sheep that are not of this sheep pen. I must bring them too. They too will listen to my voice, and there shall be one flock and one shepherd — this verse speaks to the inclusion of Gentiles in God's redemptive plan, breaking down the barrier between Jewish and non-Jewish believers. The 'other sheep not of this fold' represent all who will come to faith through Christ, regardless of ethnicity. The goal is 'one flock and one shepherd' (mia poimnē kai heis poimēn), a unified community under Christ's authority, transcending ethnic and religious boundaries. This anticipates the fulfillment of Isaiah 56:8 and the inclusion of all nations in God's salvation.
Church Fathers on John 10:16
Two evil persons have been mentioned, one that kills, and robs the sheep, another that does not hinder: the one standing for those movers of seditions; the other for the rulers of the Jews, who did not take care of the sheep committed to them. Christ distinguishes Himself from both; from the one who came to do hurt by saying, I am come that they might have life; from those who overlook the rapine of the wolves, by saying that He gives His life for the sheep. Wherefore He said…
As if He said, I love My sheep, and they love and follow Me. For he who loves not the truth, is as yet very far from knowing it.
Hence the difference of the hireling and the Shepherd. The hireling does not know his sheep, because he sees them so little. The Shepherd knows His sheep, because He is so attractive to them.