Vatican City - Pope Benedict XVI said Monday that ecumenical talks with Lutherans had run into new challenges and called for greater efforts at dialogue in the years before the 500th anniversary of the start of the Protestant Reformation.
Benedict, who has made uniting all Christians a priority of his pontificate, made the comments to Bishop Mark Hanson, president of the Lutheran World Federation, during a Vatican audience.
The federation has 140 member churches in 78 countries.
Hanson, in remarks released by his organization, thanked the pope for making Christian unity a priority, and said Lutherans agreed they had a shared responsibility to ensure that the Gospel "may truly fill the life and mission of our churches."
Both he and the pope cited a landmark 1999 Catholic-Lutheran document on salvation as evidence of strong ties between the two churches.
Benedict called the document, which officially buried a centuries-old dispute on the means of achieving salvation, a "significant milestone on our common path to full visible unity."
The pope said, however, that differences on the issue remain and need to be addressed. He repeated his hope that future ecumenical talks not deal solely with "institutional" questions of the church but delve into what he called "the true source of all ministry in the church."
"We are aware that our fraternal dialogue is challenged not just by the need to verify the reception of these shared formulations of doctrine in our respective communions, but even more so today by a general climate of uncertainty regarding Christian truths and ethical principles which formerly went unquestioned," he said.
Catholic-Lutheran talks will demand patience in the future, the pope said, but he called for renewed vigor in light of the 500th anniversary of the start of the Protestant Reformation in Germany in 2017.
"As we prepare to mark the 500th anniversary of the events of 1517, we should intensify our efforts to understand more deeply what we have in common and what divides us, as well as the gifts we have to offer each other," Benedict said in remarks released by the Vatican.