63 From this Apostolic Center of the Church of Christ, We turn Our eyes toward those who, unfortunately in great numbers, are either ignorant of Christ and His Redemption or do not follow in their entirety His teachings, or who are separated from the unity of His Church and thus are without His Fold, although they too have been called by Christ to membership in His Church. The Vicar of the Good Shepherd, seeing so many of his sheep gone astray, cannot but recall and make his own the simple but expressive words of Christ, words which are permeated through and through by the longings born of divine desire: "And other sheep I have, that are not of this fold: them also I must bring." ( John x, 16) He cannot but rejoice in the wonderful prophecy which filled even the Sacred Heart of Jesus with joy. "And they shall hear my voice, and there shall be one fold and one shepherd." May God, and We join with you and with all the faithful in this prayer, shortly bring to fulfillment His prophecy by transforming this consoling vision of the future into a present reality.
Source: Ubi Arcano Dei Consilio (Vatican.va)