Pope John Paul II has hailed the entry of 10 new nations, including his native Poland, into the European Union and said it must rediscover its Christian roots to deal with diverse cultures and religions.
He has been a staunch supporter of inserting specific reference to the continent's Christian foundations in the new European constitution.
"The unity of the European peoples, if it is to be lasting, cannot however be only economic and political," Pope John Paul told thousands of tourists and pilgrims gathered in St Peter's Square for his weekly appearance from his studio window.
The pontiff said that "the soul of Europe remains united even today because it refers to common human and Christian values."
"The history of the formation of the European nations goes hand in hand with that of evangelization. Thus, despite the spiritual crises which have left their mark on the life of the continent up to our days, its identity would be incomprehensible without Christianity," said John Paul.
"Only a Europe which doesn't remove, but rediscovers its very Christian roots, can be up to the great challenges of the third millennium: peace, dialogue among cultures and religions, the protection of creation," the pope said.
After reading his speech in Italian, the pope spoke off-the-cuff in Polish for a few minutes. He told his fellow Poles that the addition of the 10 members on Saturday concluded a process of enlargement that was set in motion by the "changes in Poland," the Italian news agency ANSA reported.
His words appeared to refer to the battle led by the Solidarity labor movement in the late 1970s and 1980s that pushed for more freedom and rights in his homeland. His championing of the Polish struggle is credited with figuring heavily in the downfall of Soviet bloc communism in Poland.
Pope John Paul II, who has made better relations with Orthodox Christians an important goal of his papacy, also called on "all believers in Christ in the West and in Eastern Europe" to cooperate in the new Europe.