Rabbi Balfour Brickner, 78, founding rabbi of Washington's Temple Sinai, rabbi emeritus of the Stephen Wise Free Synagogue in New York and an outspoken political and social activist, died of lung cancer Aug. 28 at Mount Sinai Hospital in New York. He lived in Fort Lee, N.J., and Stockbridge, Mass.

"Rabbi Brickner was a passionate man," Rabbi Ammiel Hirsch, chief rabbi of the Stephen Wise Free Synagogue, said in a statement. "He said what he meant and he meant what he said. It was exhilarating to listen to him."

Named for Lord Arthur Balfour, author of the 1917 Balfour Declaration, Rabbi Brickner was born in Cleveland, the son of a prominent Reform rabbi.

He served in the Navy during World War II, then graduated from the University of Cincinnati with a bachelor's degree in philosophy in 1948.

In 1952, he was ordained as a Reform rabbi at the Hebrew Union College-Jewish Institute of Religion in Cincinnati.

He moved to Washington that same year to become, at 26, the founding rabbi of Temple Sinai, a congregation chartered a year earlier out of an unofficial gathering of seven families who, according to the congregation's official history, "were looking for a chance to loosen the constraints of a Reform movement, which itself had become doctrinaire."

The congregation, enthusiastically ecumenical and deeply involved in politics and social issues, met in the Bethlehem Chapel of the National Cathedral before moving in the late 1950s into its permanent home at Military Drive and 31st Street.

A few years after the young rabbi arrived, The Washington Post described him as "tall, dark and handsome." Decades later, he made New York magazine's list of 50 sexiest New Yorkers, with "the looks of a rake (wavy silver mane, chiseled jaw) and the soul of a mensch."

Rabbi Brickner, who also taught biblical and post-biblical history at American University, was with Temple Sinai until 1961, when he moved to New York to join the national staff of the Union of American Hebrew Congregations, the Reform movement's central organization.

He was director of the movement's Commission on Religious Affairs and co-director of its Commission on Social Action. And he became rabbi of the Stephen Wise Free Synagogue in New York in 1980.

In both positions, he regularly spoke out on issues of the day: against U.S. involvement in Central America and corporate involvement in then-apartheid South Africa; for abortion rights, civil rights and environmental protection; and for the rights of Palestinians.

Although he was, in the words of Hirsch, "a passionate Zionist," he did not hesitate to criticize Israeli policies, frequently prompting claims of disloyalty to the State of Israel.

"It's 'My country right or wrong,' " he told the New York Times in a 1982 article about discord among U.S. Jews over Israel, "but I've never adopted that for America and I'll be damned if I'll adopt it for Israel."

"He often took positions that at the beginning were controversial, but as time went on became mainstream," Hirsch said.

Involved in the anti-Vietnam War movement, he traveled to Paris to meet secretly with leaders of the Viet Cong and then to Vietnam as part of an interfaith peace delegation.

He was one of the first American Jews to travel to Israel at the outbreak of the Yom Kippur War in 1973. Carrying journalist's credentials, he crossed the Suez Canal into Egypt with the Israeli army.

He founded Religious Leaders for a Free Choice and was a board member of the National Association for the Repeal of Abortion Laws, the National Abortion and Reproductive Rights Action League and the Planned Parenthood Federation of America.

Speaking to the annual Planned Parenthood conference, meeting in Washington in 1981, he had a question for the delegates: "Everybody knows God is a God who makes war and God is a God who makes peace. Does anybody ever think about God as a God who makes love? And if God makes love, does God wear a contraceptive when God makes love?"

During the 1980s, he hosted a nationally syndicated radio program, "Adventures in Judaism," which received a Peabody nomination and won awards. He also wrote numerous articles for various publications, including The Post, and two books, "Searching the Prophets for Values" (1981) and "Finding God in the Garden: Backyard Reflections on Life, Love and Compost" (2003).

He became rabbi emeritus at the Stephen Wise Free Synagogue in 1991 and continued writing, lecturing and taking stands on certain issues. Writing in a Planned Parenthood publication in 2002, he laid out a biblical rationale for abortion and urged religious people "to protest the Bush administration's war against women."

His marriages to Barbara Michaels Brickner and Doris Gottlieb Brickner ended in divorce.

A daughter, Elisa Brickner, died in a car accident in 1973.

Survivors include two sons from his first marriage, Rabbi Barnett Brickner of Columbus, Ohio, and Adam Brickner of Baltimore; and four grandchildren.