Both John XXIII and John Paul II, who will be canonized April 27, acted for Church unity and dedicated much of their lives and Magisterium to foster relations among Christian communities. John XXIII’s effort was highly appreciated among the Orthodox Churches; when he convoked the Second Vatican Council, representatives of both the Orthodox Churches and Protestant ecclesial communities were invited as observers of the Ecumenical Council. According to the late Cardinal Johannes Willebrands, who was for many years president of the Pontifical Council for Promoting Christian Unity, John XXIII was revered by the Russian Orthodox. Willebrands had been appointed to the pontifical council’s forerunner by John XXIII in 1960, and testified during the Roman Pontiff’s cause for canonization that as Catholics and their separated brethren discussed a possible patron for the ecumenical movement, “Russian observers asked that John XXIII himself be considered as patron of the ecumenical movement.” John XXIII’s concern for the ecumenical movement stretched back to the years he was apostolic delegate to Turkey. The homily he gave at the celebration of Pentecost in Turkey in 1944 — the last he was to spend in the country — shows the spirit of Roncalli: set in the east, his school for ecumenism. Bishop Roncalli said: “Here, we Latin Catholics of Istanbul and Catholics of Armenia, Greece, Chaldean, Syrian rite — we are a modest minority living on the surface of a vast world we are just superficially in touch with. We love to distinguish ourselves from those who do not profess our faith, from the Orthodox, Protestants, Jews, Muslims, believers or non-believers.” But, he continued, even if “diversity of race, language, education, painful contrasts of a sad past keep us in reciprocal distance, in the light of the Gospel … Christ has come to tear the walls down; he died to proclaim our universal brotherhood; the central focus of his teaching is the love that links every man to him as the first of brothers, and that links him with us to the Father.” During his pontificate, John Paul II continued John XXIII’s commitment to ecumenism. In his 1995 encyclical on commitment to ecumenism, “Ut unum sint”, he wrote that “to believe in Christ means to desire unity; to desire unity means to desire the Church; to desire the Church means to desire the communion of grace which corresponds to the Father's plan from all eternity. Such is the meaning of Christ's prayer: Ut unum sint.” He said, "the entire life of Christians is marked by a concern for ecumenism; and they are called to let themselves be shaped, as it were, by that concern.” "Thus, it is absolutely clear that ecumenism, the movement 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 the fruit borne by a healthy and flourishing tree which grows to its full stature.” One of the most important ecumenical moment of John Paul II’s papacy occurred during his trip to Greece in 2001 -- the first visit of a Pope to Greece in more than 1,200 years. The trip started in a climate of ecumenical hostility, since no representatives from the Greek Orthodox Church welcomed him upon his arrival. On May 4, he had a 30-minute meeting with the Greek Orthodox Archbishop Christodoulos of Athens. After the meeting, Archbishop Christodoulos read in public the list of “13 offences” committed by Catholics against the Orthodox, including the 1204 Sack of Constantinople. Archbishop Christodoulos complained that “no pardons” had been asked by the Catholic Church for “the furious crusades of the twelfth century.” John Paul II responded: “For the past and the present occasions, for any time the sons and daughters of the Catholic Church sinned in actions or omissions against their Orthodox brothers and sisters, may the Lord give us mercy.” He added that “Catholics feel profound regret for the plunder of Constantinople.” John Paul II and Archbishop Christodoulos then went to the Areopagus, whence they issued a joint declaration that they would “do everything in our power to see to it that Europe’s Christian roots and soul are preserved.”