Despite broad disagreements on basic policies, Ambassador Diaz said he is focusing on the values and the interests the two sides share.
"I think it's important to recognize that there are differences,” he said. “But I think it's important not to be paralyzed by those differences. The things that we have in common far exceed the things that divide us," said Ambassador Diaz.
As the ninth U.S. ambassador, Diaz said he is really "standing on the shoulders" of the "giants" that have gone before him.
Unofficial relations between the two states go back to the birth of America, when President George Washington assured Pope Pius VI that the Pope would have full freedom to appoint bishops in the new land.
It would take until President Ronald Reagan in 1984 for the U.S. to establish its first official embassy here. At that time, it was widely perceived that the U.S. president saw the Vatican and then-Pope John Paul II as an important ally in the fight against communism.
The embassy recently celebrated its 27th anniversary. Ambassador Diaz has as a staff of 19 — a formidable presence for promoting U.S. foreign policy at the world's smallest state.
"The size is really inversely proportional to the scope of influence," said Ambassador Diaz. “You can't just think of the Holy See as boxed with the Vatican City walls. We have to think of it as this vast network."
Since his Senate confirmation hearings, Ambassador Diaz has spoken of his vision for the embassy as one of “building bridges.”
And he has pursued that strategy during his 16-month tenure. He has worked diligently to build relationships not only with Vatican officials, but also with the wider institutions of the universal Church — pontifical universities, religious communities, even hospitals, non-profits and humanitarian agencies.
The embassy has sponsored several high-profile meetings to highlight areas of mutual interest.
An embassy-sponsored conference in 2009 brought professionals to the city to raise awareness of the need to stop mother-child transmission of AIDS. The embassy co-sponsored a concert with the Church aid agency Caritas to raise money for Haitian earthquake victims.
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An embassy-sponsored conference at the Pontifical Gregorian University last October encouraged members of different faith traditions to come together in "building bridges." At the event, the director of the White House's Office of Faith-Based and Neighborhood Partnerships, Joshua DuBois, gave the keynote address.
But Ambassador Diaz said much of his diplomatic work is done in one-on-one conversations — what he called "diplomacy at the table" during luncheons and dinners, and "targeted diplomacy" with Vatican contacts through more formal channels.
The issues of concern to the U.S. and the Vatican are broad and far-reaching.
"One of the greatest challenges,” he said, was how the “human family” is going to “reconcile” its “incredible diversity” of religions and cultures. This diversity, he said, “increasingly threatens to tear us apart.”
On that note, Ambassador Diaz called Pope Benedict’s annual speech to diplomats Jan. 10 “ambitious.”
The Pope used strong language to condemn religious discrimination and persecution around globe, especially in the Middle East, North Africa and China.