In 1959, while observing the annual Week of Prayer for Christian Unity in a church outside of Rome, the newly elected Pope John XXIII recorded that "out of the blue" he decided to call an Ecumenical Council, the first since 1871. Blessed Pope John XXIII's ecumenical inspiration may have come "out of the blue" literally, as a result of the prayers that had arisen from organized Anglican, Protestant, Orthodox and Catholic communities during the fifty years before his decision.
As a result of prayer and the work of the Ecumenical Council, Blessed Pope John's successor Pope Paul VI promulgated a Decree on Ecumenism on November 21, 1964, thus fulfilling one of the chief concerns of the Second Vatican Council. That Decree states, "Many Christian communions … proclaim themselves to be disciples of the Lord, but their convictions and their paths diverge, as though Christ Himself were divided. (cf. I Cor. 1:13). Without doubt, this discord openly contradicts the will of Christ, provides a stumbling block to the world, and inflicts damage on the most holy cause of proclaiming the good news to every creature."
Thirty years later, Blessed Pope John Paul II, in his Encyclical, Ut Unum Sint: On Commitment to Ecumenism, wrote, "It is absolutely clear that ecumenism, the movement of promoting Christian unity, is not just some sort of 'appendix' which is added to the Church's traditional activity. Rather ecumenism is an organic part of Her life and work, and consequently must pervade all that She is and does; it must be like fruit borne by a healthy and flourishing tree which grows to its full stature."
In Benedict XVI's first written message as Pope, he determined, "...as a primary commitment, to work without sparing energies for the reconstitution of the full and visible unity of all the followers of Christ."