WASHINGTON (RNS) With his flowing black robe and long white beard, Ecumenical Patriarch Bartholomew is a living portrait of the 2,000-year-old Orthodox Christian faith.

And yet, he says, he’s somewhat of a revolutionary.

“By calling Christianity revolutionary, and saying it is dedicated to change, we are not siding with progressives — just as, by conserving it, we are not siding with conservatives,” he said in a lecture at Georgetown University on Tuesday (Nov. 3). “The only side that we take is that of our faith, which today may seem to land us in one political camp, tomorrow another, but in truth we are always only in one camp, that of our Lord and Savior Jesus Christ.”

The speech of the Istanbul-based patriarch was one of numerous appearances by the man known for his advocacy of interfaith relations and religious freedom, and often dubbed the “green patriarch” for working to combat environmental degradation.

During his two-and-a-half week U.S. visit, he’s spoken from the banks of the Mississippi River, where he led a conference on problems affecting the world’s major bodies of water. He later traveled to New York, where he received an honorary degree from Catholic leaders at Fordham University, visited a Manhattan synagogue and conducted a prayer service at the United Nations.

The 69-year-old patriarch is the top spiritual leader of the world’s Orthodox Christians and their primary messenger to people unfamiliar with Orthodox traditions or theology.

“He’s someone who can speak a language that everyone understands,” said Elizabeth Prodromou, a Greek Orthodox Christian and director of a program on international relations and religion at Boston University. “He makes religion accessible in terms of those urgent problems that preoccupy all of us as human beings and American citizens.”

Bartholomew may speak for the grass roots but he has the ear of the powerful across Washington.

In addition to meeting with President Obama, the patriarch’s schedule includes dinner at Vice President Joe Biden’s residence, meetings with congressional leaders and Secretary of State Hillary Rodham Clinton, and sessions with ambassadors to Turkey and Greece.

He also plans to have a private breakfast with schoolmates from the Theological School of Halki that was closed by Turkey in the 1970s. In his April meeting with Obama in Turkey, he discussed the closed seminary, which Obama has urged Turkish lawmakers to reopen. A congressional resolution welcoming Bartholomew to Washington also called for the school to be reopened.

A White House statement on Obama’s Tuesday meeting with Bartholomew noted that the president reaffirmed his support for the seminary.

“He also took the opportunity to reiterate the U.S. commitment to confronting global climate change and to applaud the Ecumenical Patriarch for his work on global interfaith dialogue,” the Obama administration said.

At Fordham, Bartholomew congratulated the Jesuit school on its ecumenical efforts — including offering Orthodox Christian studies — and called for greater cooperation across faiths.

“As faith communities and as religious leaders, it is our obligation constantly to pursue and persistently to proclaim alternative ways to order human affairs, ways that reject violence and reach for peace,” he said in an Oct. 27 speech. “Human conflict may well be inevitable in our world; but war certainly is not.”

At many stops — from Fordham to Georgetown to the White House — Bartholomew returned to his priority of caring for the environment, saying those who “tyrannize the earth” are committing sins.

“It’s very significant to have so prominent an Orthodox figure not talking just to the church but very much talking to the world,” said the Rev. Alexander Rentel, assistant professor of canon law and Byzantine Studies at St. Vladimir’s Orthodox Theological Seminary in Crestwood, N.Y.

His blending of faith and environmental concerns pleases Orthodox Christians like Rentel, a priest in the Orthodox Church in America who was struck by the patriarch’s image of “late antiquity mixed with Huck Finn” as he visited the Mississippi River in New Orleans.

“As an American Orthodox, it somehow brings my worlds together in a different way,” he said.