99 When I say that for me, as Bishop of Rome, the ecumenical task is "one of the pastoral priorities" of my Pontificate, I think of the grave obstacle which the lack of unity represents for the proclamation of the Gospel. A Christian Community which believes in Christ and desires, with Gospel fervour, the salvation of mankind can hardly be closed to the promptings of the Holy Spirit, who leads all Christians towards full and visible unity. Here an imperative of charity is in question, an imperative which admits of no exception. Ecumenism is not only an internal question of the Christian Communities. It is a matter of the love which God has in Jesus Christ for all humanity; to stand in the way of this love is an offence against him and against his plan to gather all people in Christ. As Pope Paul VI wrote to the Ecumenical Patriarch Athenagoras I: "May the Holy Spirit guide us along the way of reconciliation, so that the unity of our Churches may become an ever more radiant sign of hope and consolation for all mankind".
Source: Ut Unum Sint (Vatican.va)