The pope has offered wide-ranging messages of reconciliation to Muslims since coming to Turkey on Tuesday, including appeals for greater understanding and support for Turkey's effort to become the first Muslim nation in the European Union.

But Benedict also has set down his own demands.

The pope repeated calls for greater freedoms for religious minorities — including the tiny Christian community in Turkey — and denounced divisions between Christians as a "scandal."

Benedict has made reaching out to the world's more than 250 million Orthodox a centerpiece of his papacy and has set the difficult goal of "full unity" between the two ancient branches of Christianity, which split in the 11th century over disputes including papal authority.

"The divisions which exist among Christians are a scandal to the world," the pope said after joining Ecumenical Patriarch Bartholomew I to mark the feast day of St. Andrew, who preached across Asia Minor and who tradition says ordained the first bishop of Constantinople, now Istanbul.

The homage of the Orthodox feast day Liturgy also was highly significant to Roman Catholics. Andrew was the brother of St. Peter, who was martyred in Rome and is considered the first pope.

In a joint statement, the pope and patriarch stressed the need to "preserve Christian roots" in European culture while remaining "open to other religions and their cultural contributions."

The comments could send conflicting signals to Turkey after the Vatican suggested there was room in the EU for its first Muslim member. They could also serve as a rallying point for groups opposed to bringing a predominantly Muslim country into the bloc.

The pope also recalled how the faith was shaped by the encounters of early Christians with the scientific and intellectual traditions of ancient Greece. It was the same theological backdrop — faith and reason — that was the basis for his explosive remarks in September in which he quoted a medieval Christian emperor who described Muhammad's teachings as "evil and inhuman."

The pope avoided any direct mention of Islam after praying with Bartholomew at the St. George Church in Istanbul, capital of Christian Byzantium before falling to Muslim forces in 1453.

The echoes of the city's turbulent history were among Benedict's stops.

Haghia Sophia, once a spiritual center of Christianity, was converted to a mosque in the 15th century. The site became a museum following the secular reforms that formed modern Turkey in the 1920s.