Jesus talks about this new humanity —
I have [a]other sheep [beside these] that are not of this fold. I must bring those also, and they will listen to My voice and pay attention to My call, and they will become [b]one flock with one Shepherd. – John 10:16
Jesus is saying that His death is going to bring non-Jews into the flock also. It’s implied in the statements that present Jesus as the Saviour of the whole world. The result of bringing the sheep into the fold is creation of a new humanity “in Christ.”
Paul contrasts the new humanity with the old as well. Those who are in Adam experience the consequence of Adam’s sin, where those who are in Christ experience the result of Jesus’ saving act.
While the death of Christ makes it possible for other sheep to come into Christ’s flock, the way this will happen today is through the Church going out and bringing them in. John 10:16 then is a missionary verse.
This saying of Jesus becomes very personal; for it is a dream which every one of us can help Jesus to realize. Men cannot hear without a preacher; the other sheep cannot be gathered in unless someone goes out to bring them in. Here is set before us the tremendous missionary task of the Church. And we must not think of that only in terms of what we used to call foreign missions. If we know someone here and now who is outside his love, we can find him for Christ. The dream of Christ depends on us; it is we who can help him make the world one flock with him as its shepherd. – William Barclay
It is fitting that taking this verse in context which describes the death of Jesus climaxes with the missionary challenge.
The author examines the New Testament strand by strand in a way that will be quite familiar to those who have been brought up on Vincent Taylor. And he begins with the Synoptic Gospels. Our Lord did not identify Himself with men in such a way as to obscure the difference between His life and ours. Denney sets out to emphasize the difference rather than the identity, and for that reason prefers the word ‘ substitute ‘ to ‘ representative ‘. The Passion sayings are examined in turn, and the significance of the Baptism and Temptation of Jesus, implying His double role as both Messiah and Suffering Servant, is fully recognized. The word from heaven at His Baptism was indeed the true index of His life. That is why from the outset Christ sees the two paths that lie before Him and chooses the one ” which He knows will set Him in irreconcilable antagonism to the hopes and expectations of those to whom He is to appeal “. That there was a divine • must • about His· career is increasingly evident as the gospel narratives proceed, and this ‘must’ included death. Messiahship as He unfolded it spelt death. ” This was the first and last thing He taught about it, the first and last thing He wished His disciples to learn.” It is the very soul of His vocation. Our Lord’s thought dwells constantly in that circle of ideas to be found in the Old Testament concept of sacrifice and supremely in Isaiah liii. This culminates in the Last Supper. What Jesus does and says there is “the focus of revelation, in which the Old Testament and the New are one “. The meaning of His death as propitiation is demonstrated there, “for propitiation is merely a mode of mediation, a mode of it, no doubt, which brings home to us acutely what we owe to the Mediator, and makes us feel that, though forgiveness is free to us, it does not cost Him nothing ”. – James Denny
We also have in this verse the first statement about the universal Church. This is a theme the Church has often failed to preach and practice, but it is certainly a unique feature that the gospel can offer to a world torn by communal prejudice and strife.