Istanbul, Dec. 3, 2007 (CWNews.com) - Cardinal Walter Kasper led a high-level Vatican delegation to Istanbul to join Patriarch Bartholomew I in celebrating the feast of St. Andrew, the patron of the Constantinople see, on November 30.

Following what has become an annual tradition, the secretary of the Pontifical Council for Christian Unity brought the greetings of the Pope to the Constantinople patriarchate. (Patriarch Bartholomew has sent his own delegation to Rome each year, to join the Pope in celebrating the feast of Sts. Peter and Paul on June 29.) This year Cardinal Kasper brought the Orthodox prelate a signed copy of the Pope's newly published encyclical, Spe Salvi.

In his message to Patriarch Bartholomew, the Holy Father recalled his trip to Turkey last year, when he himself joined in the ceremonies for the feast of St. Andrew in Constantinople. The Pontiff also welcomed the progress achieved during an October meeting of the joint Catholic-Orthodox theological commission, in sessions held at Ravenna, Italy.

The ecumenical discussion was "not without some difficulties," Pope Benedict conceded in his message, and he voiced the hope that "these may soon be clarified and resolved."

The Pope added that ecumenical work is "according to the will of Christ our Lord." In light of the problems facing the contemporary world, he said, that work is "all the more urgent because of the many challenges facing all Christians, to which we need to respond with a united voice and with conviction.

In his own homily during the November 30 celebration, Patriarch Bartholomew made a similar point, saying that ecumenical unity is more necessary than ever in the face of advancing secularism and materialism. Christians must join together to lead a recovery of the sacred, he said, relying on the efficacy of the sacraments and the soundness of Christian doctrine.