67 Unfortunately, however, the sort of unity whereby all believers in Christ profess the same faith, practise the same worship and obey the same supreme authority, is no more evident among the Christians of today than it was in bygone ages. We do, however, see more and more men of good will in various parts of the world earnestly striving to bring about this visible unity among Christians, a unity which truly accords with the Divine Saviour's intentions, commands and desires; and this to Us is a source of joyous consolation and ineffable hope. This desire for unity, We know, is fostered in them by the Holy Spirit, and it can only be realized in the way in which Jesus Christ has prophesied it: "There will be one fold and one shepherd." (61)
Source: Aeterna Dei Sapientia (Vatican.va)