Vorspan died on Saturday at the age of 95, according to the Union for Reform Judaism.

URJ President Rabbi Rick Jacobs described Vorspan as “one of the towering giants of Jewish social justice.”

“Al blazed a trail of courage and conscience that so many of us have walked,” Jacobs said in a tweet. “Not since the biblical prophets Amos, Hosea, and Micah walked the earth have we been led by such an inspiring justice leader. Our Reform Movement and our world are bereft, for he cannot be replaced.”

In 1964, Vorspan was jailed with a group of Reform rabbis who at the request of the Rev. Martin Luther King, Jr. joined in the civil rights protests in St. Augustine, Florida. “We came as Jews who remember the millions of faceless people who stood quietly, watching the smoke rise from Hitler’s crematoria. We came because we know that, second only to silence, the greatest danger to man is loss of faith in man’s capacity to act,” he later wrote about his reason for joining the protests.

Vorspan, who had fought in the U.S. Navy during World War II, was an early and vociferous opponent of the Vietnam War, which led Sen. Thomas J. Dodd, a member of the Senate Subcommittee on Internal Security, to call him “a vociferous minority” rather than holding a mainstream Jewish opinion.

He also criticized Israel’s treatment of the Palestinians, writing in a piece in the New York Times magazine in 1988 at the beginning of the first Palestinian Intifada that “Israelis now seem the oppressors, Palestinians the victims.”

In 1953, Vorspan convinced Rabbi Maurice Eisendrath, who was then president of the Union of American Hebrew Congregations, to create the Commission on Social Action, which worked with the Union and the Central Conference of American Rabbis to guide and shape social action in Reform communities and in Washington, D.C., according to the Religious Action Center’s website.

He then pressed the Union to create the Religious Action Center in order to make the voice of the Reform movement heard in the halls of Congress. The RAC was voted into existence at the 1961 UAHC Biennial in Washington, D.C.

He c0-authored with Rabbi David Saperstein the 1998 book “Jewish dimensions of social justice: tough moral choices of our time,” which provides Jewish perspectives and moral policy analysis on issues ranging from abortion to capital punishment and from the Mideast peace process to religious freedom in Israel and the United States.

He was married to his wife, Shirley, for 72 years until her death on Aug. 27, 2018.