Born in Bethlehem, Pennsylvania and raised in Philadelphia, Rabbi Kessler served in the Air Force for nearly three years, flying 18 missions over Europe with a crew of the 15th Air Force during World War II. He responded to a "higher calling" and was ordained in 1951 at the Jewish Theological Seminary where he also earned a Masters of Hebrew Literature (MHL) and Doctor of Divinity (D.D.).

Rabbi Kessler arrived in West Hartford in 1954 to lead a brand new synagogue, Beth El. He was awarded life tenure ten years later and in 1992 became Rabbi Emeritus. In retirement, Rabbi Kessler continues to participate in life at Beth El when he is not traveling around the world or to Israel (he's been there more than 30 times since 1949) - or called to serve another synagogue's spiritual needs.

Rabbi Kessler was past national chair of the Rabbinic Cabinet of the United Jewish Appeal. He has served on the National Rabbinical Assembly, as a member of the Executive Council, the Committee of Law and Standards, the Placement Commission, and as Chairman of a National Rabbinical Assembly Convention and the Bio-Ethics Committee. At the Jewish Theological Seminary, he has been on the Board of Overseers, the Chancellor's Rabbinic Cabinet, and has served as the Director of "Gateways," a Seminary-sponsored national outreach program to the inter-married. For more than 25 years he was on the Board of Governors of the Synagogue Council of America.

A major part of Rabbi Kessler's life has been devoted to civil rights. He was among the Freedom Riders of the Civil Rights movement and participated in demonstrations in Birmingham in 1963 and Selma in 1965. Over the years he has served on the Human Rights Commission of Hartford, the Human Experimentation Committee of the University of Connecticut Medical School, the Martin Luther King Commemoration Committee, and the United World Federalists of Greater Hartford where he was chair. Rabbi Kessler has been a member of the Boards of Directors of the Community Renewal Team (CRT), the Urban League, the Urban Coalition of Greater Hartford and the Connecticut Interfaith Housing and Human Services Commission. He was also on the faculty of Trinity College Department of Religion from 1967-1973 and the Philosophy Department at the University of Hartford. In 1992, Trinity College honored him with an honorary Doctorate.