Pope Benedict XVI and Archbishop Christodoulos, head of the Orthodox Church of Greece, signed a joint declaration Thursday calling for inter-religious dialogue and reaffirming their opposition to abortion and euthanasia.

The declaration underscored improved relations between the Catholic and Orthodox churches, which have been divided for nearly 1,000 years and are still split by long-standing questions of doctrine.

It was the first visit to the Vatican by Christodoulos — except for a visit to attend Pope John Paul II's funeral in April 2005. Both leaders expressed their willingness to keep up their dialogue.

"For its part, the Catholic Church has the strong will to undertake everything possible for our 'rapprochement,' in view of reaching full communion between Catholics and Orthodox," the pope said. "For now, we are in favor of pastoral collaboration on all possible levels."

Christodoulos said he hoped that dogmatic obstacles would be overcome.

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Relations between the two branches of Christianity have been cool. But calls for greater dialogue were strengthened when Benedict visited Turkey Nov. 28-Dec. 1 and met with Ecumenical Patriarch Bartholomew I, spiritual leader of the world's 250 million Orthodox Christians.

In speeches delivered before signing the declaration in the papal library, Benedict and Christodoulos also warned against the risk of growing secularization in modern European society and the need to defend Christian values.

"Europe ... cannot be an exclusively economic reality. Catholics and Orthodox are called to offer their cultural, and above all spiritual, contribution," Benedict said. "They in fact have the duty to defend the continent's Christian roots, which have shaped it throughout the centuries."

"It is necessary to develop cooperation between Christians in each country of the EU, so as to face the new risks that confront the Christian faith, which is to say growing secularism, relativism and nihilism," the pope told the archbishop in the speech delivered in French.

The declaration is a 12-chapter document that affirms the "need to continue on the path of constructive theological dialogue" as an essential tool toward re-establishing Christian unity.

"We think religions have a role to play to ensure the (promotion) of peace in the world and that they must not become hotbeds of intolerance and violence," said the declaration. "We call on all religious leaders to pursue and strengthen inter-religious dialogue."

The declaration also called on scientists to respect human life. It said human dignity and integrity should be respected "in all phases of its existence, from conception to natural death" — a Vatican catch phrase to express opposition to abortion and euthanasia.

Benedict has repeatedly campaigned for defense of human life and traditional family.

The archbishop arrived on Wednesday for a four-day visit, which reciprocates John Paul II's trip to Athens in 2001.